NVS TGT Science held on 29th Nov 2022 shift 1 (Previous Year Paper)

The correct answer is The National Air Sports Policy, 2022.

Key Points

• Union Civil Aviation Minister Jyotiraditya Scindia has announced the National Air Sports Policy-2022 for the first time in New Delhi.
• Recently, Civil Aviation Minister Jyotiraditya Scindia announced the National Air Sports Policy-2022 for the first time in the country.
• Through this policy, 11 air sports including aerobatics, ballooning, gliding, parachuting, powered aircraft and rotorcraft will be promoted.

Important Points

• National Air Sports Policy-2022
• The aim of this increasing interest in aerial sports, the government is planning to encourage many programs related to it.
• This was the reason that just a few days ago, the Central Government had issued a National Air Sports Policy draft and now yesterday i.e. on June 7, the National Air Sports Policy-2022 was issued for the first time.

Education is fundamental for achieving full human potential, developing an equitable and just society, and promoting national development.

Key Points

• The NEP 2020 strongly promotes the integration of professional, technical, and vocational education with general higher education.
• The goal is to move towards a comprehensive, multidisciplinary higher education system.
• This means engineering, medical, and other professional institutions will be part of larger multidisciplinary universities or clusters.

Hint 

• Option 2: Correct. NEP 2020 aims to grant greater autonomy to HEIs to foster innovation and excellence.
• Option 3: Correct. NEP 2020 calls for the revitalization of Agricultural education by incorporating greater synergy with the allied disciplines and local practices.
• Option 4: Correct. This aligns with the policy's central philosophy of ensuring quality education and fundamental learning for all citizens.

Hence, 'Professional education will be separated from higher education system' is incorrect with reference to NEP 2020.

The correct answer is NBT.

Key Points

• On 2 October 2022, the Ministry of Education launched the Young, Upcoming and Versatile Writers Scheme.
• It is a program of the Ministry of Education for the young, budding, and versatile writers of the country.
• For this, the National Bank Trust (NBT), India under the Ministry of Education has been made the implementing agency of the scheme.

Important Points

• Young, Upcoming, Versatile, Authors (PM – YUVA)
• It is a program of the Ministry of Education for the young, budding and versatile writers of the country.
• For this, the National Bank Trust (NBT), India under the Ministry of Education has been made the implementing agency of the scheme.
• Its job is to implement the scheme phase-wise under the stated phases of mentorship to the youth scheme.
• The books prepared under this scheme will be published by the National Book Trust (NBT).

The correct answer is The Governor of the State.

Key Points

• The Consolidated Fund has been constituted under Article 266(1) of the Constitution of India. All the expenditure of the government is borne from this fund.
• The Contingency Fund of India established under Article 267(1) of the Constitution is a sum of money earmarked for a specific purpose that is placed at the disposal of the President for making advances to meet immediate unforeseen expenditure unless by authority Authorization should not be pending.

Important Points

• Government Funds and Public Accounts
• Consolidated Fund: According to Article 266(1) of the Constitution, the money received by the government from all revenues, such as customs duty, excise duty, income tax, estate duty, other taxes and fees, and the recovery of loans given by the government, they are all credited to the Consolidated Fund. After the approval of the Parliament, the government bears all its expenses from this fund. That is why it is called the Consolidated Fund of India.
• Contingency Fund: As per Article 267 of the Constitution, the Parliament has been given the power to establish a fund. This fund is called the Contingency Fund of India. It is a fund into which money is deposited from time to time by laws passed by the Parliament. This fund is under the control of the President and to meet the emergent needs of the country, funds are made available to the government by the President from this fund.
• Public Account of India: According to Article 266(2) of the Constitution, all other public money received by or on behalf of the Government of India is credited to the Public Account of India.

The correct answer is Ashleigh Barty.

Key Points

• Australian tennis player Ashleigh Barty won the Australian Open women's title by defeating American Danielle Collins on 29 January 2022.
• Spain's Rafael Nadal won the Australian Open men's singles final on 30 January 2022.

Important Points The winner's list of Australian Open Tennis Title 2022:

The correct answer is 2022 – 2032.

Key Points

• The United Nations has declared 2022 as the International Year of Artisanal Fishing and Aquaculture and Glass.
• international year declared by the United Nations
• 2022 - 32: International Decade of Indigenous Languages
• 2021 - 30: United National Ecological Restoration Day.
• 2019 - 28: Decade of Peace, Nelson Mandela Decade
• 2018 - 27: International Decade for Poverty Alleviation

Important Points UNDP was established in the year 1965 by the United Nations General Assembly. It ensures expert advice, training and grant assistance to developing countries, with an emphasis on providing assistance to the least developed countries.

The correct answer is Benjamin List and David MacMillan.

Key Points The 2021 Nobel Prize in Chemistry was awarded to Benjamin List and David McMillan for the development of asymmetric organocatalysis.

• 2021 Nobel Prize winner
• Medicine - David Julius and Ardem Patapoutian
• Physics - Tsukuro Manabe, Claus Hasselmann and Giorgio Perisic
• Chemistry - Benjamin List and David W.C. macmillan
• Literature- Abdul Razak Gurnah – Novelist from Tanzania
• Peace - Maria Ressa and Dmitri Muratov
• Economic Sciences - David Card, Joshua Angrist and Guido Imbens

Important Points

• 2022 Nobel Prize in Chemistry 
• Carolyn R. Bertozzi, K. Barry Sharpless and Morton Meldal were awarded the 2022 Nobel Prize in Chemistry 'for the development of click chemistry and bioorthogonal chemistry'.
• Sharpless (won a second time) coined the term 'click chemistry' extensively.
• Meldal, independently discovered a special chemical structure called 'triazole' which has many important applications.
• Bertozzi worked to develop click reactions that could work inside living organisms, calling them 'bioorthogonal' reactions (a term he coined).

The correct answer is Finland.

Key Points

• Recently the 'Global Happiness Report 2022' has been published by the United Nations Sustainable Development Solutions Network.
• Finland has been declared the world's happiest country for the fifth time in a row, followed by Denmark.
• This year marks the 10^th anniversary of the 'Global Happiness Report'.
• According to the 10^th edition of the World Happiness Report 2022, a total of 146 countries were ranked in this year's index. In this, India has been ranked 139 out of 149 countries while Finland is at the top.

Important Points

• Global Happiness Report:
• The World Happiness Report published in 2012 is based on two main ideas:
• Happiness or life assessment is to be measured through surveys and
• To identify the major factors that determine the well-being and quality of life in the country.
• The report usually ranks 150 countries based on a number of factors such as real GDP per capita, social support, healthy life expectancy, freedom of decision-making, and perception of corruption.
• This year, 146 countries have been ranked in the report.

The correct answer is Lt. Cdr. Mritunjay Kumar.

Key Points

• President of India Draupadi Murmu has approved 107 gallantry awards for the Armed Forces and Central Armed Police Forces (CAPF) on the eve of Independence Day. In India, the President is the Supreme Commander of the Armed Forces.
• Gallantry Awards approved by the President include 3 Kirti Chakras, 13 Shaurya Chakras, 2 times Sena Medals (Gallantry Awards), 81 Sena Medals (Gallantry Awards), 1 Navy Medal (Gallantry Awards), and 7 Vayu Sena Medals (Gallantry Awards).

Important Points

• Jawans awarded with Shaurya Chakra-
• 1. Indian Army - 8 (one posthumous)
• Major Nitin Dhania
• Major Amit Dahiya
• Major Sandeep Kumar
• Major Abhishek Singh
• havaldar ghanshyam
• Lance Naik Raghvendra Singh
• Sepoy Karanveer Singh (Posthumously)
• Gunner Jasbir Singh (posthumously)
• 2. Navy - 1
• Lieutenant Commander Mrityunjay Kumar
• 3. CRPF - 1
• Assistant Commandant Amit Kumar

The correct answer is 

Key Points

• Passenger’s Name Record Information Regulations 2022
• The salient points of the Regulations are as under:
• The Regulations require the operator of Aircrafts (i.e airlines) to transmit specified information electronically to the designated Customs System. Passengers are not required to individually submit any information to Customs, neither do they need to furnish any additional information to the Airlines on account of these regulations. Airlines are already collecting this information under the aegis of the Chicago Convention on International Civil Aviation.
• The data exchange between the Airlines and the Customs Systems is through the PNRGOV EDIFACT message format. This is a standard electronic message format endorsed jointly by the World Customs Organisation (WCO), International Civil Aviation Organisation (ICAO) and the International Air Transport Association (IATA) and is widely used internationally.
• Although some data elements included in the Regulations are available from other sources, the objective of these regulations is to obtain this data in advance of departure or arrival of the passengers for analytics by the Customs Risk Management System.
• The information collected is subject to strict information privacy and data protection and there are adequate legal and administrative safeguards built in. Processing of the information to reveal ethnicity, race, religious or philosophical beliefs, health etc. is strictly prohibited. Hardware and software necessary for data protection has already been envisaged. The information received is used for further processing only by a senior officer of the rank of Principal Additional Director General/Additional Director General.
• In normal course, the data collected is stored only for five years after which it is disposed of by depersonalisation or anonymisation. The Regulations provide for an extensive and independent system audit and security audit to prevent misuse of the information.

As per the given information,

Five houses A, B, C, D and E are in a line.

• House A is to the right of B.

• B is to the right of D.

• E is to the left of C and right of A.

​

Therefore, the final arrangement will be:

Clearly, 'A' is in the middle.

Hence, the correct answer is "A".

As per the given information,

A, B, C and D are four friends. Who is the oldest in the group?

I. D is older than B and C but younger than A.

• A > D > B / C

→ Clearly, A is the oldest. Thus, statement I alone is sufficient to answer.

II. C is younger than A but older than B.

• A > C > B

→ Here, the position of D is not fixed so we can not conclude that who is the oldest. Thus, statement II alone is not sufficient to answer.

Clearly, statement I alone is sufficient while II alone is not sufficient to answer.

Hence, the correct answer is "I alone is sufficient while II alone is not sufficient".

Statement:

Cases of dengue fever are rising in the city.

Course of Action:

I. Mosquito breeding sites should be traced and treated immediately.

→ The sites in which mosquitoes that breed dengue thrive should be traced and treated. Because by reducing the habitat available for these mosquitoes can help prevent dengue.

So, statement I follows. 

II. Mosquito net or repellants should be used during the night.

→ The mosquito net or repellants should be used during the night can help repel mosquitoes from biting you.

So, statement II follows. 

Hence, the correct answer is "Both I and II follow".

Statements:

1. W > R < P
2. T ≤ R
3. Q ≥ W = S

Conclusions:

I. Q > P → False (As Q ≥ W = S and W > R < P → Q ≥ W > R < P, no clear relation between Q and P, so it is false)

II. T ≤ S → False (As Q ≥ W = S; W > R < P and T ≤ R → T < R, so it is false)

Hence, the correct answer is "Neither conclusion I nor II is true".

By using the following symbols in the table given below, we can draw the following family tree:

Statement: A man pointing to a boy said, ‘He is the son of the only daughter of the father of my brother.’

Here, the boy is the son of the only daughter of the father of Man's brother that is man's brother's father is also the father of the man and the only daughter of his father will be his sister and the son of his sister will be the 'Nephew' of the man.

Clearly, 'the boy is 'Nephew' of the Man'.

Hence, the correct answer is "Nephew".

**Given:**1, 4, 27, 16, ?, 36, 343

The logic follows here is:

Hence, the correct answer is "125".

The logic follows here is:

Hence, the correct answer is "U".

As per the given information,

A river flows from North to South, and then turns right and takes a semi-circular round around a huge building. Then it turns right by 90°. After flowing some distance, it turns left again by 90°.

Thus, the following diagram can be drawn:

Clearly, the river is flowing in 'From West to East'.

Hence, the correct answer is "From West to East".

The logic follows here is,

Roughage adds bulk to food and makes its passage through the stomach easier, thus preventing constipation.

Thus, Both Assertion and Reason are true and Reason is the correct explanation for Assertion. 

Hence, the correct answer is "Both (A) and (R) are true and (R) is the correct explanation of (A)."

As per the given information,

The Venn diagram that best represents the relationship among Doctors, Teachers, and Women is:

Here,

• Some Women can be Teachers or Doctors.
• Some Women can be both Teacher and Doctors**.**

Hence, the correct answer is "option (4)".

A computer device is any programmable electronic device whether portable or stationary. 

Key Points

• Computer devices can be categorised into two types Input and Output.
• An input device is a piece of hardware or equipment that facilitates data entry into a computer.
• Input devices are electromagnetic devices that receive information or a set of instructions from the outside world and translate that information into a format that is machine-readable and intelligible.
• For Example Keyboard, Mouse, Joystick, Light Pen, Track Ball, Scanner, TouchPad, Digitizer, and Microphone.

Thus, Plotter cannot be used as an input device on a computer system.

Additional Information

• An output device is any piece of computer hardware that transforms data into a form that can be understood by humans.
• Some examples of output are Monitor, Printer, Plotter, Projector,  Speakers, Headphones, LCD Screen, Sound Card, and Video Card.

Malware is computer software that can harmful to computers. 

Key Points

• Malware has been purposefully created to disrupt a computer, or server, leak sensitive data, gain unauthorised access to data, and deny access to data.
• Malware can be categorized into one or more subtypes such as computer viruses, worms, Trojan horses, ransomware, spyware, adware, rogue software, wiper and keyloggers.
• A Trojan horse is a programme that has been downloaded and installed on a computer that pretends to be harmless but is actually harmful.
• Trojans are typically transmitted through some type of social engineering such as tricking a user into opening an email attachment or ads on social media or somewhere else.

Thus, An innocent-looking email attachment or a program downloaded and installed on a computer that appears to be harmless, but is in fact malicious and executes whatever task the attacker designed it to carry out is called Trojan Horse. 

Additional Information

• A computer virus is a form of malware that has the ability to multiply and propagate once it has been run on a machine.
• Spamming is the practice to send messages at a large scale without their consent through electronic messaging platforms.
• Phishing is a form of social engineering assault that is frequently employed to obtain user information, such as login credentials and credit card details.

Malware is computer software that can harmful to computers. 

Key Points

• Malware is computer code that can damage your laptops and desktops as well as the data they contain.
• The term antivirus software comes from the fact that it was first created to find and eliminate computer viruses.
• Antivirus is a program to find and get rid of viruses and other types of dangerous software from computers.
• Its function is to prevent, identify, and eliminate malware.
• It frequently operates in the background to deduce malware on computers, servers, and mobile devices and stop it from spreading.

Thus, software, which prevents, scans, detects and removes malware from a file or a computer system is called Antivirus.

Additional Information

• Cookies are a piece of information from a website that is saved in a web browser for subsequent retrieval by the website.
• Web browsers are programmes used to access websites.
• Firewall is a network security device used to monitor and filter incoming and outgoing network traffic

​A computer network is a collection of two or more networked computers. 

Key Points

• A computer network connection can be created using either cable or wireless media used for sharing files and resources.
• There are various types of networks: Personal Area Network (PAN), Local Area Network (LAN), Metropolitan Area Network (MAN), and Wide Area Network (WAN).
• A Personal Area Network is built around one individual.
• It includes a computer, a phone, or a personal digital assistant.
• PAN can be used to connect these personal gadgets to a digital network and the internet by establishing communication between them.

Thus, PAN types of networks she is using for taking backups.

Additional Information

• WAN is a computer network that is spread over a big geographic area.
• MAN is a computer network spanning an entire city, a college campus, or a small area.
• LAN is a group of computers and related peripherals that are interconnected in a constrained space.

Bytes are digital information is stored in units. 

Key PointsThe largest capacity in bytes can typically be found in the hard disk of a computer. Here's why:

• Hard Disk: Modern hard disks can reach capacities up to several terabytes (TB). As of my last update in 2021, hard disks of up to 20TB were common.
• RAM: The capacity of the RAM is usually much less than hard disk capacity. Most modern systems come with 8GB to 64GB of RAM, which is factor of thousand less than the hard disk storage when looking from GB to TB.
• DVD-ROM: A standard single-sided, single-layer DVD-ROM can store 4.7GB of data. Dual-sided or dual-layer DVDs can store more, but their capacity is still much less than either hard disks or typical RAM sizes.
• Pen Drive: While Pen Drives (also known as USB Flash Drives) are quite portable and convenient, their storage capacity is typically less than a hard disk. Capacities range widely, but as of my last update in 2021, commonly available sizes were typically up to 2TB, less frequent than hard disks of the same size.

So, based on a standard configuration, a hard disk generally has the largest capacity in bytes. However, remember that the specific capacity of these components can vary widely depending on the exact model and configuration of the computer system.

Additional Information

• The equivalent of a single character, such as the letter B, a comma, or a percentage sign, is represented by a single byte.
• Eight consecutive binary digits (bits) make up a byte, each of which can be either a 0 or a 1.

Microsoft Office is a group of client software, server software, and services created by Microsoft. 

Key Points

• Microsoft Office suits contain Microsoft Word, MS Access, Microsoft Excel, Microsoft PowerPoint, etc.
• Microsoft Word is a word processor that may be used to create papers, letters, reports, and other types of writing of professional quality.
• It includes sophisticated capabilities that give you the best formatting and editing options for your files and projects.
• Some of the Features of MS Word are Templates, Image formats, WordArt, Macros, Page Layout and etc.
• It can be used by teachers to make question papers and assignments.

Thus, MS Word software under Microsoft Office Package is best suited. 

Additional Information 

• MS PowerPoint is used to make presentations for personal and professional purposes.
• MS Excel is a spreadsheet program used to save and analyse numerical data.
• ​Microsoft Access is an information management tool used to store all kinds of information for reporting, analysis, and reference.

Shortcut keys for computers are a group of one or more keys that produce a specific command to be executed.

Key Points

• A command is a clear instruction that tells a computer programme to carry out a certain operation or function.
• The copy command often moves files from one area to another.
• Crtl+C is a shortcut command to help users to copy.
• The paste command is used to handle both single and multiple files.
• After the copied text content from a document, if users want to paste that copied content into another document.
• The shortcut for the paste command is Ctrl + V.
• The Paste command is used to copy and paste data from the virtual clipboard onto the area where the mouse cursor is now located.

Thus, Ctrl + V keyboard shortcut paste command. 

Additional Information

• Some of the Shortcut commands are mentioned below: 
• Ctrl + C: Copy
• Ctrl + P: Print a document
• Ctrl+E:  Aligns the line

Microsoft Office is a group of client software, server software, and services created by Microsoft. 

Key Points

• Microsoft Office suits contain Microsoft Word, MS Access, Microsoft Excel, Microsoft PowerPoint, etc.
• Microsoft Word is a word processor that may be used to create papers, letters, reports, and other types of writing of professional quality.
• MS PowerPoint is used to make presentations for personal and professional purposes.
• MS Excel is a spreadsheet program used to save and analyse numerical data.
• In Microsoft programmes, the F7 key is frequently used to spell and grammar checks a document.
• The highlighted word is checked in the Thesaurus with Shift+F7.

Thus, MS Word software under Microsoft Office Package is best suited. 

Additional Information

• Some other uses of F7
• Sift+F7: Thesaurus
• Ctrl+F7: Move
• Atl+F7: Next spell and grammar checks

Software is a collection of instructions or computer programmes used to run computers to carry out particular activities.

Key Points

• Software instructs a computer to run.
• It can be categorized into types: Application software and System software.
• System software is a category of a computer programme made to run the hardware and application software of a computer.
• It can be further divided into Operating systems, Device drivers, and Utility Software.
• Utility software helps to examine, configure, optimise, or manage a computer
• Some examples of Utility software are  Antivirus, File Management Systems, Compression Tools, Disk Management Tools,  Disk Cleanup Tools and Disk Defragmenters.

Thus, Antivirus software is an example of Utility Software.

Additional Information

• Programming Language is a method of notation for creating computer programmes.
• Operating Systems are important sets of programmes that control resources and offer services to other software.
• Application software is used by end users and is created to perform a particular purpose.

The location of the webpage is indicated by the web address.

Key Points

• The location of the webpage is indicated by the web address.
• The URL (uniform resource locator) is another name for the web address.
• It identifies the location of the web page that is being displayed as well as other pertinent details.
• It contains the scheme (https), subdomain (www), top-level, second-level (textbook), and subdirectory(.com).
• A URL is nothing more than the Web address of a particular resource.

Thus, the URL is the alternate name for the address of a webpage on a website.

Additional Information

• IP Address is a unique address used to identify a device on the internet or a local network.
• A domain name is an Internet resource name that all Web servers.

‘Teaching’ means “impart knowledge or skill, give instruction or lessons, instill and inspire with”. By analyzing this meaning, we can say that teaching is an activity that facilitates learning.

Key Points

• It is an intimate contact between a more mature personality and a less mature one**,** which is designed to further the education of the latter.
• According to Edmund Amidon, Teaching is an interactive process primarily involving classroom talk, which takes place between teacher and pupil, and occurs during certain definable activities.
• The teaching process takes the learner along with himself in order to stimulate, promote and endorse learning.
• It is a process that involves stimulation, guidance, direction, and encouragement of learning among children.
• Teaching is not a haphazard activity but a goal-directed activity that leads to predetermined behavior.

Hence, we conclude that teaching is an interactive process.

‘Teaching’ means “impart knowledge or skill, give instruction or lessons, instill and inspire with”. By analyzing this meaning, we can say that teaching is an activity that facilitates learning.

Key Points

Objectives of teaching-

• It aims at bringing about desirable changes in the behavior of the learners or their cognitive structure.
• It develops the thinking ability of the students.
• It fosters the potential of students to grow and bloom.
• It makes children apply disciplinary knowledge to real-life situations.

Hence, we conclude that one major objective of teaching is to bring desirable change in learners' behavior.

A teacher is a facilitator who tries to satisfy the educational needs of the learners in such a manner that they play an important and positive role for the upliftment of society.

• An effective teacher is a multifaceted professional playing the different roles of a facilitator, curriculum creator, counsellor, and role model for the learners.

Key PointsCharacteristics of a good teacher-

• He/she should communicate warmth, understanding, and empathy to his/her students.
• He/she should generate enthusiasm for learning in his/her classroom.
• He/she should create a positive classroom learning environment through a climate of acceptance, caring, feeling of being safe and secure, etc.
• He/she should not teach without proper lesson planning as without lesson plans, teachers are less likely to be clear about the learning objectives, activities, and materials needed for the class.
• He/she should be the master of his/her subject and should be capable of giving explanations at different levels so that he/she can reach all students.

Hence, we conclude that a good teacher should not teach without proper lesson planning.

Note:- We have provided the most appropriate answer to this question. The answer provided by the board is ambiguous.

Learning is the process of acquiring new understanding, knowledge, behaviors, skills, values, attitudes, and preferences.

• A learner refers to someone who is eager to learn something practical, theoretical and skillful in the field of mental, physical, academic, social or emotional levels.

Key Points

Characteristics of a learner-

• Readiness- Motivation, interest, and curiosity to learn.
• Attitudes and habits- Must be positive, must pay attention to the teacher, and must be ready to accept his/her mistakes.
• Absence of anger and jealousy as it reduces learning abilities.

Hence, we conclude that prior preparation of the topic to be taught is not an important characteristic of a learner as it is done by the teacher while lesson planning.

A teacher is a facilitator who tries to satisfy the educational needs of the learners in such a manner that they play an important and positive role for the upliftment of society.

• An effective teacher is a multifaceted professional playing different roles of a facilitator, curriculum creator, counselor and a role model for the learners.

 Key PointsCharacteristics of an effective teacher-

• Teacher has the moral responsibility of taking into consideration the ability and aptitude of learners and guiding them accordingly.
• Teaching should incorporate such activities which shall strengthen the bonding between all in the classroom and all get equal opportunity of expression.
• Teacher must teach that character building is higher than academic achievement.
• The teacher should reflect on social issues. He will become a better educator by developing social awareness and respect for the students' feelings.
• Teacher should not avoid the inquisitiveness of learners related to sex, attraction, drugs, stress, abuse, suicide, bribery, etc.

Hence, we conclude that social issues should be ideally reflected in the teaching of a teacher.

Teaching methods are referred to as the strategies adopted by the teacher to assist children throughout the learning process. Effective learning of children depends on the method the teacher adopts.

Key PointsBy adopting a good teaching method, a teacher should help students in -

• participating actively in the teaching-learning process.
• providing a scope for learning something by doing.
• solving problems in all spheres of life.
• thinking independently and constructing knowledge of their own.
• achieving effective learning outcomes.
• addressing the diverse needs of learners.
• conveying experiences, skills, and information to them.

Hence, we conclude that by adopting a good teaching method, a teacher should help students in solving problems in all spheres of life.

Teaching methods are referred to as the strategies adopted by the teacher to assist children throughout the learning process. Effective learning of children depends on the method the teacher adopts.

Key Points 

Interactive/participative method:

• Interactive methods ensure the active participation and involvement of children which play a very vital role in learning and shaping the personality of a child.
• This method is based on a situational appraisal of what should be learned or done right now, considering the circumstances of the students and the teacher. They demand a participatory understanding of various aspects and domains.
• This method can be used to impart moral education because moral development occurs through social interaction.
• For example, Lawrence Kohlberg studied moral development by posing moral dilemmas to groups of children as well as adolescents and adults and knowing their views about the situation.

Hence, we conclude that moral education can be best imparted by the interactive/participative method. 

Additional Information

• In teacher-centered methods, all the instructional activities and procedures are under the control of the teacher.
• In learner-centered method, the teacher "becomes a resource rather than an authority."
• Content-focused methods- Both the teacher and the students must be able to relate to the material being taught in this method. Generally, this denotes that the knowledge and abilities that are to be imparted are viewed as valuable or extremely significant.

Teaching learning materials (TLMs), also known as teaching aids, facilitate a teacher in achieving the learning objectives formulated by her/him prior to starting teaching-learning activities.

• The role of teaching-learning resources in the classroom is to make learning real, practical, and fun for children.

Key Points

• Stories - Stories at the secondary level opens door to a new world for children. It allows children to discover new concepts and knowledge, learning key life lessons by listening to an interesting, fascinating story.
• Anecdotes are relatively brief stories that are relevant to the subject at hand. They typically give personal insight or experience.

Stories and anecdotes-based films help in-

• Arousing children’s curiosity and stimulating their imagination.
• Entertaining them and appealing to their sense of adventure.
• Clarifying and dealing with their emotions, giving recognition to their problems and suggesting solutions.
• Developing their intellect and self-confidence and inner resources.
• For example- Topics like "World Peace" can be introduced through stories and anecdotes-based films as it improves students' communication abilities, inspires them to study the past and present, and forges bonds amongst students in the class through shared experiences.

Hence, we conclude that the best teaching aid for teaching the topic "World Peace" to senior secondary students is stories and anecdotes based films.

Additional Information 

• Audio aids: These aids refers to the materials or devices which call upon the auditory senses and thus help individuals to learn through listening e.g. Radio broadcasts, Cassette, and CD player.
• Charts help to display data and invite further exploration of a topic.

Adolescence is termed as a period in the development of the human being when the growing individual begins to transform into an adult-like physical form accompanied by improvement in mental faculties. 

• It lasts from 12 to 18 years and is considered as the period of development and adjustment during the transition between childhood and adulthood.

Key Points

• Adolescence has traditionally been considered a more difficult period in development than the preceding middle childhood years for both adolescents and their parents.
• Adolescence has been thought of as a period of “storm and stress” – a time of heightened emotional tension resulting from the physical and glandular changes that are taking place in this period.
• At the same time, adolescents have immense mental, physical, and emotional potential.
• Their thinking becomes more abstract, they perceive long-range options and develop reasoning.
• This is a critical time in life because the experiences, knowledge, and skills acquired in adolescence have important implications in adulthood.

​Hence, we conclude that both A&R are true but R is not the correct explanation of A.

Teaching learning materials (TLMs), also known as instructional aids, facilitate a teacher in achieving the learning objectives formulated by her/him prior to starting teaching-learning activities.

• The role of teaching-learning resources in the classroom is to make learning real, practical, and fun for children. It also helps in bringing novelty and freshness to classroom teaching as they relieve learners from anxiety, fear, and boredom.

Key PointsImportance of teaching-learning material- 

• Motivate Learners – Capturing attention is the first step to any learning. Teaching learning resources help in capturing the attention of learners in the classroom.
• Help in Longer Retention of Information – The more the number of sensory channels involved in interacting with teaching learning resources, the longer will be the retention of information.
• Facilitate Holistic Learning – To achieve varied objectives, varied learning experiences need to be provided, which can be done through the use of teaching-learning resources.
• Makes learning meaningful – it makes learning real, practical, and pleasurable for the students.
• Facilitate change in Attitude – Teaching learning resources also help in changing the attitude of learners towards learning in general and subject content in particular.
• Application of Theoretical Knowledge into Practical Applications – Teaching learning resources show the application of theoretical knowledge into practical applications.
• Teaching learning resources help in making learning fun in the classroom- Students enjoy the novelty of handling new objects and learn new concepts through them.

Hence, we conclude that in classroom teaching-learning, the use of teaching-learning material by the teacher is significant because teaching-learning material makes learning more meaningful.

Correct answer: 3)

Concept:

• When two or more substances are present in any proportion is known as a mixture.
• A mixture is said to be heterogeneous if the composition of the substance throughout is not uniform.
• There are two or more distinct phases in a heterogeneous mixture.
• The components of a heterogeneous mixture are visible with the naked eye or at least under a microscope.
• A mixture is said to be homogeneous if the composition of the substance throughout is uniform.
• The components of a homogeneous mixture cannot be seen by the naked eye or even under a microscope.

Explanation:

• The mixtures which contain physically distinct parts and have non-uniform compositions are called heterogeneous mixtures.
• Mixtures of sodium chloride and sulphur is an example of a heterogeneous mixtures.
• An aqueous solution of ferrous sulphate forms a homogeneous solution.
• An alloy of iron, nickel and carbon is a homogeneous mixture of metals and non-metals.
• A mixture of hydrogen, oxygen and nitrogen gases is a homogeneous mixture.

Conclusion:

Thus, A mixture of sulphur and sodium chloride powder is a heterogeneous mixture.

Correct answer: 2)

Concept:

• Isoelectronic species are elements or ions that have the equal number of electrons.
• In isoelectronic species, as the nuclear charge increases, the force of attraction by the nucleus on the electrons also increases.
• Variation of size among isoelectronic species: As the nuclear charge increases, the force of attraction by the nucleus on the electrons also increases. As a result, the ionic radius decreases.

Explanation:

• Isoelectronic species = they are the species belonging to different atoms or ions which have same number of electrons but different magnitude of nuclear charge.
• Now, A positive charge denotes the loss of an electron & A negative charge denotes the gain of an electron by a species.
• Number of electrons in the given species are as:
• Li: 3
• Na: 11
• K: 19
• S^2-: 18
• Cl^- : 18
• Ar : 18
• K⁺ : 18
• Ca⁺ : 19
• Ne : 8
• F : 9
• S-2, Cl-1, Ar are contains same number of electrons . So they are isoelectronics.

Conclusion:

Thus, species: S-2, Cl-1, Ar are isoelectronic species.

Correct answer: 3)

Concept:

• An ion is an atom or molecule with a net electrical charge.
• Ions are of two types, cation and anion.
• The cation has a positive charge and the anion has a negative charge.
• These charges are due to the addition or subtraction of negative particles in the atom.
• When an ion is formed, the number of protons does not change.

Explanation:

• Ion :- It is an electrically charged atom or molecule formed by loss or gain of electrons.
• Ion formed by loss of electron is called cation.
• Ion formed by gain of electron is called anion.
• An ion is an atom or molecule that has a different number of electrons than protons.

Conclusion:

Thus, in an ion the number of electrons and protons can never be equal is the correct statement.

Correct answer: 3)

Concept:

• One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions).
• The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant.
• The concept of the mole can be used to convert between mass and number of particles.
• The number of Moles = Mass of substance / Mass of one mole.

Explanation:

The number of moles of CH₄ in container A:

Given the mass of CH₄= 10 g

Molar mass of CH₄= 16 g/mol

\(Number : of : molecules = \frac{Given: mass}{Molar : mass}\times Avogadro's : Number(N_{A})\)

Number of molecules = \(\frac{10}{16}\times N_{A}\)

Number of molecules = 0.625N_A

The number of moles of N2 in container B:

Given mass of N2= 10 g

Molar mass of N2= 28 g/mol

Number of molecules = \(\frac{10}{28}\times N_{A}\)

Number of molecules = 0.357NA

The number of moles of H2 in container C:

Given the mass of H2= 10 g

Molar mass of H2= 2 g/mol

Number of molecules = \(\frac{10}{2}\times N_{A}\)

Number of molecules = 5NA

The number of moles of CO2 in container D:

Given the mass of CO2= 10 g

Molar mass of CO2= 44 g/mol

Number of molecules = \(\frac{10}{44}\times N_{A}\)

Number of molecules = 0.227NA

Conclusion:

Thus, container C would have the maximum number of molecules of the gas.

Correct answer: 3)

Concept:

• The molar mass of a substance is the mass in grams of one mole of the compound.
• In a substance, the amount of entities present e.g. atoms, molecules, ions, is defined as a mole.
• A mole of any substance is 6.022×10²³ molecules.

Explanation:

Option 1: 10 moles of H2O

Molar mass of H2O = 18 g/mol

Mass = moles x molar mass

= 10 x 18

= 180 g

Option 2: 0.5 moles of C12H22O11

Molar mass of C12H22O11 = 342 g/mol

Mass = moles x molar mass

= 342 x 0.5

= 171 g

Option 3: 2.0 moles of CaCO3

Molar mass of CaCO3 = 100 g/mol

Mass = moles x molar mass

= 100 x 2.0

= 200 g

Option 4: 4.0 moles of CO2 

Molar mass of CO2  = 44 g/mol

Mass = moles x molar mass

= 44 x 4.0

= 176 g

Conclusion:

Thus, 2.0 moles of CaCO3 have the highest mass.

Correct answer: 4)

Concept:

• The Rutherford atomic model was also known as the "Rutherford nuclear atom" and the "Rutherford Planetary Model".
• In 1911, Rutherford described the atom as having a tiny, dense, and positively charged core called the nucleus.
• The light, negatively charged, electrons circulated around this nucleus, much like planets revolving around the Sun.

Explanation:

• Rutherford put forward the nuclear model of an atom, which had the following features:
• There is a positively charged centre in an atom called the nucleus.
• Nearly all the mass of an atom resides in the nucleus.
• The electrons revolve around the nucleus in circular paths.
• The size of the nucleus is very small as compared to the size of the atom

Mistake Points 

• B. Electrons have negative charge: While true, this statement is more a general fact about atoms and not a unique feature of Rutherford's model. Rutherford did acknowledge electrons' negative charges but did not focus on their specific properties in his model.

Conclusion:

Thus, the correct statements are A and D.

Correct answer: 3)

Concept:

• Alloy, a metallic substance composed of two or more elements, as either a compound or a solution.
• The components of alloys are ordinarily themselves metals, though carbon, a nonmetal, is an essential constituent of steel.
• Solder is commonly used in, electronics, heating, air conditioning, mechanical, fire sprinkler, and other similar systems as well as radiator manufacturing, repair, and sheet metal work.

Explanation:

• Solder is an alloy of lead and tin. It is used for joining pieces of metal.
• It contains 50% lead and 50% tin.
• Solder is suitable for welding electrical wires because it has a low melting point.
• Hence, it is used for soldering (or welding) electrical wires together.
• It has a relatively lower melting point than lead and tin.

Conclusion:

Thus, statements A and C are true about Solder.

Correct answer: 1)

Concept:

• Valency is the combining power of an element. Elements in the same group of the periodic table have the same valency.
• The valency of an element is related to how many electrons are in the outer shell.
• Valency is simply equal to the number of electrons gained, lost, or shared by an atom of an element to achieve the nearest noble gas configuration.

Explanation:

Electronic configuration of element A: 2, 7

So, the valency of element A is 1.

Electronic configuration of element B: 2, 8,1

So, the valency of element B is 1.

Electronic configuration of element C: 2, 8,2

So, the valency of element C is 2.

Electronic configuration of element D: 2, 8,3

So, the valency of element D is 3.

Conclusion:

Thus, the elements having the same valency are A and B.

Correct answer: 2)

Concept:

• Atomic number (Z):  Atomic number of an element is equal to the number of protons present in the nucleus of an atom.
• Since an atom is electrically neutral, thus the number of protons and the number of electrons are equal.
• Mass Number (A): The total number of protons and neutrons present in the nucleus of an atom is called the mass number.
• It is denoted by A.
• The protons and neutrons together are called nucleons.

Explanation:

• Number of electrons in element X =18
• The number of neutrons present = 20.
• Atomic number = number of protons = number of electrons in neutral atom = 18 .
• Mass number = number of protons + number of neutrons = 18+20 = 38
• So, the atom is represented as \({_{18}^{38}X}\)

Conclusion:

Thus, the correct representation of the element X is \({_{18}^{38}X}\)

Concept:

• The cell is the structural and functional unit of life.
• Cells contain various cell organelles such as the nucleus, mitochondria, Golgi body, endoplasmic reticulum, lysosomes, plastids, ribosomes, vacuoles, etc.
• Cells are bounded by cell membranes.
• On the basis of the presence or absence of a distinct membrane-bound nucleus, cells are divided into prokaryotic and eukaryotic cells.
• Cells carry out physiological processes such as digestion, excretion, secretion, defense, memory, recognition, transport of gases, nutrients, etc.

Important Points

Statement A: INCORRECT

• Protoplasm is jelly-like, colourless, transparent, and viscous living part of the cell, that comprises cytoplasm, cell organelles, nucleus, and nucleoplasm.
• Various organic and inorganic substances like proteins, fats, hormones, and enzymes all make up the protoplasm.
• The cytoplasm is a semi-fluid matrix that occupies the main arena of cellular activities in both plant and animal cells.
• The cytoplasm denotes the matrix that occurs between the cell membrane and the nuclear membrane.
• Whereas, the protoplasm includes the cytoplasm, as well as all the organelles within them.

Statement B: CORRECT

• Lysosomes are membrane-bound vesicular structures formed by the process of packaging in the Golgi apparatus.
• The enzymes are released from the Golgi apparatus in tiny vesicles that eventually fuse with the acidic endosomes of the Golgi apparatus, becoming complete lysosomes.
• Lysosomes are filled with almost all types of hydrolytic enzymes, hydrolases - lipases, proteases, and carbohydrates. These enzymes are optimally active at the acidic pH.
• Golgi bodies are the reticular structures of eukaryotic cells that are principally involved in transporting, modifying, and packaging proteins and lipids.

Statement C: INCORRECT

• Mitochondria, nuclei, and plastids have their own DNA.
• These organelles are also called semi-autonomous cell organelles.
• However, all these organelles do not make their own structural proteins:
• Most of the chloroplast (plastid) proteins are encoded by the nuclear genes.
• The mitochondrial proteins are synthesized on cytosolic ribosomes and then imported into the organelle.
• For the nuclear proteins, the RNA and ribosomes are exported out of the nucleus, for protein translation to take place in the cytosol. The newly synthesized proteins are then imported back into the nucleus.

Statement D: CORRECT

• Mitochondria are sausage-shaped or cylindrical double membrane-bound cell organelles.
• Mitochondria are the sites of aerobic respiration.
• They produce cellular energy in the form of ATP, hence they are called the "powerhouse of the cells".

Hence, the correct answer is option 4 - B and D only.

Concept:

• Cells are the basic structural and functional units of life.
• Cells contain different kinds of cell organelles to perform different physiological functions.
• It contains both membrane-bound and non-membrane-bound cell organelles.
• Eukaryotic cells have a nucleus, mitochondria, Golgi complex, lysosome, vacuoles, etc. while prokaryotic cells lack such membrane-bound organelles.
• Ribosomes are found in both eukaryotic as well as prokaryotic cells.

Explanation:

• Within the cell, ribosomes are not only found in the cytoplasm but also within mitochondria and plastids.
• They possess 70S ribosomes, smaller than that cytoplasmic ribosomes.
• These ribosomes resemble prokaryotic ribosomes, which provides an evidence of the endosymbiotic theory.
• According to this theory:
• Some prokaryotic organisms functioned in symbiosis with other organisms to perform photosynthetic (chloroplast) or respiratory (mitochondria) functions.
• Later these symbionts evolved as a single eukaryotic organism, where the prokaryotes became double-membraned organelles.
• Mitochondria and plastids also have their own single circular DNA.
• Mitochondria and plastids are commonly called semi-autonomous cell organelles.

Additional Information

Lysosomes:

• These are membrane-bound vesicular structures filled with almost all types of hydrolytic enzymes, hydrolases - lipases, proteases, and carbohydrates.
• These enzymes are able to digest carbohydrates, proteins, lipids, and nucleic acids.

Golgi apparatus:

• They are the reticular structures of eukaryotic cells that are principally involved in transporting, modifying, and packaging proteins and lipids.
• It is the major site of the formation of glycoproteins and glycolipids.

Endoplasmic reticulum:

• The ER is the tiny tubular structure scattered in the cytoplasm, involved in the synthesis of protein and lipid and secretion.
• On the basis of the presence or absence of ribosomes on the surface of ER, it is two types- the smooth and rough endoplasmic reticulum.

Vacuoles:

• Vacuoles are membrane-bound spaces that contain water, sap, excretory products, other materials, etc.
• In plant cells, vacuoles occupy up to 90% of the volume of the cells.

Hence, the correct option is (2).

Key Points

• The endoplasmic reticulum is a part of the endomembrane system.
• These are tiny tubular structures scattered in the cytoplasm and consist of membrane-bound channels, tubules, sacs, or vesicles.
• On the basis of the presence of ribosomes ER of two types rough and smooth endoplasmic reticulum.
• If ribosomes are attached to the endoplasmic reticulum then it is called a rough endoplasmic reticulum and if there are no ribosomes on the endoplasmic reticulum then it is called a smooth endoplasmic reticulum.

Explanation:

• The proteins and lipids which are essential for building the cell membrane are manufactured in the Endoplasmic reticulum (ER).
• Rough ER is frequently observed in the cells actively involved in protein synthesis and secretion.
• The Smooth ER is the major site for the synthesis of lipids.
• In animal cells, lipid-like steroidal hormones are synthesized in SER.
• ER also acts as an internal support for cytoplasm.
• Plasma membrane lipids and proteins are synthesized by the endoplasmic reticulum through the process known as membrane biosynthesis.

Additional Information

Mitochondria:

• These are sausage-shaped, cylindrical double membrane-bound cell organelles.
• Mitochondria are the sites of aerobic respiration.
• They produce cellular energy in the form of ATP, thus they are called the "powerhouse of the cell".
• The mitochondrial matrix contains circular DNA, 70S ribosomes, and enzymes that take part in protein synthesis and respiration respectively.

Plasma membrane:

• It is a selectively permeable outer layer of the cell.
• PM is composed of lipids that are arranged in a bilayer.
• The important functions of PM include the transport of materials, mechanical barrier, cell division, formation of intercellular junctions, osmosis, endocytosis, and secretion, and it also ensures cellular integrity.

Golgi apparatus:

• Golgi apparatus are membrane-bound cell organelles with flat or disc-shaped sacs, tubules, and vesicles.
• Its important functions include the storage, modification, and packaging of biochemical compounds.
• It is also the major site of the formation of glycoproteins and glycolipids.

Hence, the correct answer is Endoplasmic reticulum.

Concept:

• A tissue is a group of cells having a common origin and usually performing a common function.
• Plant tissues are classified into two groups, meristematic and permanent tissues.
• The plant tissue has the ability to divide actively throughout its life, which is called meristematic tissue.
• Both the primary as well as secondary meristems are completely grown and cells become structurally and functionally specialized and lose the ability to divide, such cells are known as permanent tissues.

Important Points

Statement A: INCORRECT

• Apical and intercalary meristems are meristematic tissues.
• Apical meristems are present at the tips of the roots and shoots.
• They help in the elongation of stems and roots and also increase the height of the plants.
• The intercalary meristems are present at the internodes or the base of the leaves.
• It helps to increase the length of the internode.

Statement B: CORRECT

• Collenchyma tissues are simple permanent tissues.
• Cells may be oval, spherical, or polygonal in shape and often contain chloroplasts.
• These long and thick-walled tissues occur in layers below the epidermis in dicotyledonous plants.
• Collenchyma consists of cells that are much irregularly thickened at the corners due to the deposition of cellulose, hemicellulose, and pectin.
• They provide mechanical support to the growing parts of the plant such as the young stem, petiole of a leaf, etc.

​Statement C: CORRECT

• Meristematic tissues have the ability to enlarge, stretch, divide, and differentiate into other types of cells when they mature.
• The cells may be oval or rounded or polygonal in shape and all are living.
• Meristems have a large nucleus but lack vacuoles.
• Vacuoles are mainly used to store food or waste materials.
• Meristematic cells are involved in cell division and growth; they are not involved in food synthesis and also do not produce much wastes.
• Thus, young meristems do not require vacuoles.
• Intercellular space between cells is also absent in meristems.

Statement D: CORRECT

• Parenchyma tissues are simple permanent tissues.
• The cells of parenchyma are generally isodiametric and they may be oval, spherical, round, polygonal, or elongated in shape.
• They are loosely packed, having intercellular spaces.
• Parenchyma performs other functions like photosynthesis, secretion, etc.

Hence, the correct option is (4) B, C and D only.

Key Points

Given: In an experiment, a student removed the tip of a sugarcane plant. It was observed that the plant is still growing in length.

• The above observation may be due to the presence of intercalary meristem.
• Sugarcane is a monocot plant and contains intercalary meristems.
• Intercalary meristems are the meristematic tissues that are present in stems at the base of nodes and leaf blades.
• These meristems can proliferate and regenerate new cells of the plant body that are removed intentionally or not.

Additional Information

Apical meristems - 

• These occur at the tips of roots and shoots.
• They are responsible for root and shoot expansion.

​Cambium - 

• It produces secondary permanent tissue and is responsible for secondary growth.
• The meristematic layer that is responsible for cutting off vascular tissues, xylem and phloem, is called the vascular cambium.

Lateral meristem - 

• The meristem occurs in the mature regions of roots and shoots of many plants, particularly those that produce a woody axis and appear later than the primary meristem called lateral meristem.
• Lateral meristems are responsible for secondary growth, which increases stem girth and thickness.

Hence, the correct option is (3).

Key Points

Given: While cycling, a student met with an accident in which two long bones of his right hand were dislocated.

• The possible reason for the above-stated dislocation is a ligament break.
• Ligaments attach one bone to another, thus the breakage of the ligament can be the reason for the dislocation of bones.
• Ligaments are dense regular connective tissue and are strong and elastic in nature.
• The radius and ulna are the two long bones in the hand.
• A strong band of fibers called an annular ligament is found on the head of the radius that retains it in contact with the radial notch of the ulna.
• The student must have broken this ligament that dislocated these long bones of the hand causing a fracture.

Additional Information

Tendon:

• Tendons are dense regular connective tissues that connect bones and muscles.
• These are tough, inelastic, and fibrous in nature.
• According to the question, two long bones of the hand are dislocated, so a tendon break is not possible.

Skeletal muscles:

• Skeletal muscle tissues are closely attached to the skeletal bones and maintain the structural framework of the body.
• Skeletal muscles are connected to bones by tendons, and they create all the movements of body parts in relation to one another.
• The breakage of skeletal muscles cannot be responsible for the dislocation of bones as bones are joined by ligaments.

Areolar tissue:

• Areolar tissues are the loose connective tissues present beneath the skin.
• It serves as a support framework for epithelium, supports the internal organ, and also helps in tissue repair.

Hence, the correct option is (2) ligament break.

Concept:

• Whittaker in the year 1969 came up with the concept of five kingdom classification.
• He classified all the living organisms into five kingdoms- Monera, Protista, Fungi, Animalia and Plantae
• The plant kingdom can be further classified as- Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.

Important Points

A- Bryophyta

• They are atracheophytic, archegoniate, and amphibious cryptogams.
• Various mosses and liverworts fall under the classification Bryophyta.
• They are commonly found growing in the moist and shaded areas in the hills.
• Bryophytes can live in the soil, but they depend on the water for sexual reproduction.
• They have thallus like body and possess rootlike and leaf like structures.
• Their main plant body is haploid.

B- Gymnosperms

• Their seeds are naked without a fruit wall.
• The ovules in these plants are not enclosed by any ovary wall and remain exposed.
• Gymnosperms are heterosporous and sporophylls aggregate to form cones.
• Most of the plants are perennial and woody.
• They contain xylem tissue for water conduction.
• The xylem is without vessels (trachea) and phloem lacks companion cells.

C- Pteridophyta

• They are archegoniate, embryophytic, tracheophytic cryptogams.
• Ferns and horsetails fall under the Pteridophyta.
• They are found growing in cool, damp, shady places. They also grow well in sandy soils.
• Evolutionarily they are the first plants to posses the vascular system - xylem and phloem.

D- Thallophyta

• Thallophytes are the organisms that posses a thallus like body.
• The body is not differentiated into stem, roots and leaves.
• They are atracheophytes (vascular tissues are absent).
• Lichens and algae fall under thallophyta.

Therefore statements B and C are correct.

Concept:

• R.H. Whittaker gave the five kingdom classification, according to which organisms can be classified into five kingdoms:
• Monera, Protista, Fungi, Plantae, Animalia
• Animalia can be classified on the basis of presence and absence of notochord into the following phyla:

Porifera ⇒ Coelenterata ⇒ Ctenophora ⇒ Platyhelminthes ⇒ Aschelminthes, ⇒ Annelida ⇒ Arthropoda ⇒ Mollusca ⇒ Echinodermata ⇒ Hemichordata ⇒ Chordata

• Phylum Chordata is divided into three subphyla: Urochordata, Cephalochordata, and Vertebrata.
• The sub phylum Vertebrata can be again classified into classes - Pisces, Amphibia, Reptilia, Aves, Mammalia.
• Oviparous - refer to animals that lay eggs.
• Viviparous - refer to animals that give birth to young ones.

Important Points

Pisces - 

• Pisces are the true jawed vertebrates.
• They are exclusively aquatic organisms and they bear fins.
• They can have a bony or cartilaginous skeleton.
• Lateral line organs or neuromast organs help in detecting the water currents.
• Exoskeleton consists of dermal scales and bony plates..
• They can be viviparous or oviparous.
• Many of the fishes under the class Chondrichthyes are viviparous.
• Fishes under the class Osteichthyes are mostly oviparous.

Amphibia - 

• These can live both on terrestrial and aquatic habitat (amphibious).
• Two pairs of pentadactylous limbs are present.
• They have three-chambered heart.
• Amphibians breath through their skin, as well as their lungs in some cases.
• Amphibians are poikilothermic animals.
• They are oviparous and they lay eggs in water.

Reptilia - 

• Reptiles are poikilotherms.
• They have creeping or crawling mode of locomotion.
• Their body is covered by dry and cornified skin, have scales or scutes.
• Gaseous exchange is primarily pulmonary.
• They have tympanum which represents their ear.
• Heart consists of two atria and and incompletely divided ventricle therefore incomplete double circulation occurs.
• They are mostly oviparous.

Aves - 

• Aves is a class of homeotherms, and includes birds.
• They are bipedal and their forelimbs are modified into wings.
• Exoskeleton consists of epidermal feathers claws on toes and beak.
• They respire through lungs and air sacs are connected to these lungs.
• The heart is four chambered.
• Fertilization is internal and all birds are oviparous.

Mammalia - 

• The presence of mammary glands (modified sweat glands) is the characteristic feature of these organisms.
• Body is covered by hair which is epidermal in origin.
• They have two pair of limbs adapted for different activities like running, walking, climbing etc.
• They are homoiotherms,
• They are viviparous.
• The Primates show female reproductive cycle called the Menstrual cycle and non primates show oestrous cycle.

From the above points we can conclude that statements A, B and D are correct.

Hence, the correct answer is option 3.

Important PointsPisces/fishes characteristic features-

• Pisces are the true-jawed vertebrates.
• They are exclusively aquatic organisms and they bear fins.
• They can have a bony or cartilaginous skeleton.
• Lateral line organs or neuromast organs help in detecting the water currents.
• Exoskeleton consists of dermal scales and bony plates.
• They can be viviparous or oviparous.
• The Pisces can be further classified into two different classes 
• Chondrichthyes - Have cartilaginous endoskeleton
• Osteichthyes - Have bony endoskeleton
• Many of the fishes under the class Chondrichthyes are viviparous.
• Fishes under the class Osteichthyes are mostly oviparaous.

Explanation:

Dogfish - 

• Scoliodon is also known as dog fish.
• It is a true fish and falls under the class Chondrichthyes.
• They have streamlined body with cartilaginous endoskeleton.

Jellyfish - 

• Jellyfish is not a true fish
• It falls under the phylum Coelenterata (Cnidaria)
• They have stinging cells also called cnidoblasts or cnidocytes in the body.

Silverfish - 

• Silverfish is an insect.
• It belongs to the phylum Arthropoda.

Starfish - 

• Starfish is not a fish.
• It falls under the phylum Echinodermata
• They have water vascular system which is their characteristic feature.

Hence, the correct answer is option 1.

Correct answer: 4)

Concept:

• Respiration is the process in which the cells of an organism obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP (energy).
• Incomplete combustion is a type of combustion in which the combustible substances react partially with oxygen.
• An oxide that exhibits the property of acids is called acidic oxide.
• Since they are acidic, they react with a base to form a salt.

Explanation:

• In respiration, the by-products are water and carbon dioxide molecules produced by the breakdown of carbohydrates.
• Carbon monoxide is produced due to incomplete combustion because, in the limited space inside a gas heater (or a car engine), there is not enough oxygen to completely oxidize the hydrocarbon fuels.
• Chlorine is a highly effective method of disinfection. So it is used in water purification systems.
• Non-metal oxides are acidic in nature. So CO₂ is an acidic oxide.

Conclusion:

Thus, the correct option is D.

Concept:

Speed:

• It is defined as the rate of change of distance per unit of time.
• Formula, Speed, \(v=\frac{ds}{dt}\) where ds = change is distance, dt = change in time
• It is a scalar quantity because it has only magnitude but not direction.
• The slope of distance vs time graphs represents speed.

Explanation:

• The slope of distance vs time graphs represents speed.
• From the graph, the slope of object A is minimum while the slope of object D is maximum.
• So, the A is the slowest and the D is the fastest.

Concept:

Speed:

• It is defined as the rate of change of distance with respect to time.
• Formula, Speed, \(v=\frac{ds}{dt}\) where, ds = change in distance, dt = change in time
• The SI unit of speed is m/s.
• It is a scalar quantity because it has only magnitude but not direction.

​Acceleration:

• It is defined as the rate of change of speed with respect to time.
• Formula, acceleration, \(a=\frac{dv}{dt}\), where v = velocity, t = time
• The SI unit of acceleration is m/s².

Calculation:

An object is covering distances in direct proportion to the square of the time elapsed, x = kt², where k = constant

Speed, \(v=\frac{ds}{dt}\)

v = 2kt

Acceleration, \(a=\frac{dv}{dt}\)

a = 2k

Hence, the acceleration is constant.

Concept:

Force:

• The push or pull on an object with mass causes it to change its velocity.
• Force is an external agent capable of changing a body's state of rest or motion.
• It is defined as the product of mass and acceleration.
• Formula, force, F = ma, where m = mass, a = acceleration
• The SI unit of force is Newton (N).
• It is a vector quantity because it has a magnitude and a direction.

Calculation:

Given,

The mass of the block, m = 2 kg

Constant speed, v = 0.5 m/s

The block is sliding with a constant speed, so acceleration, a = 0 m/s²

Force, F = ma

F =  2 × 0 = 0 N

Hence, the force required to keep the block sliding with the same speed is 0 N.

Concept:

Newton's Second law of motion:

• Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration
• Formula, Force, \(F=\frac{dP}{dt}\), where dP = change in momentum, dt = change in time.
• Force, F = ma, where m = mass, a = acceleration
• It is applied to identify the amount of force needed to make an object move or make it stop.

Explanation:

• While catching a fast-moving cricket ball, a fielder on the ground gradually pulls back his hand back with the moving ball.
• In doing so, he experiences a smaller force for a longer interval of time to catch the ball.
• Resulting in a lesser impulse on his hands and hence it will not hurt the hands of the fielder.

Concept:

Average speed:

• The average speed is the total distance traveled by the object in a particular time interval.
• Formula, average speed, \(v_{avg}=\frac{Δ x}{Δ t}\), where Δx = total distance traveled, Δ t = time interval
• The average speed is a scalar quantity.
• It is represented by the magnitude and does not have direction.

Calculation:

Consider the below diagram for which motion is as shown below

 

Time taken to travel first half distance,

\(t_1=\frac{L/2}{v_1}\)

The time is taken to travel the second half distance,

\(t_2=\frac{L/2}{v_2}\)

The total time is taken, t = t₁ + t₂

Average distance, \(v_{avg}=\frac{L}{t_1+t_2}\)

\(v_{avg}=\frac{L}{\frac{L/2}{v_1}+\frac{L/2}{v_2}}\)

\(v_{avg}=\frac{2v_1v_2}{v_1+v_2}\)

Concept:

Force:

• It is defined as the product of mass and acceleration.
• Formula, F = ma, where m = mass, a = acceleration
• The SI unit of the force is Newton.

Equation of motion:

• The first equation of motion: v = u + at
• The second equation of motion: s = ut + 0.5 at²
• Third equation of motion: 2as = v² - u²
• Here, v = final velocity, u = initial velocity, a  = acceleration, t = time

Calculation:

Given,

The mass of the ball, m = 50 g = 50 × 10^-3 kg

From the graph, 

The initial velocity, u = 20 cm/s, The final velocity, v = 0 cm/s, Time, t = 10 s

From the first equation of motion,

v = u + at

\(a=\frac{v-u}{t}\)

\(a=\frac{0-20}{10}=-2~ cm/s^2 \)

= - 0.02 m/s²

The force exerted on the table, 

F = ma

F = 50 × 10^-3 × (- 0.02) = - 0.001 N

Here, the negative sign indicates that the direction of force is opposite.

Concept:

Friction force:

• The force that resists the sliding or rolling of one solid object over another.
• Frictional forces, such as the traction needed to walk without slipping, may be beneficial, but they also present a great measure of opposition to the motion

Force:

• It is defined as the product of mass and acceleration.
• Formula, F = ma, where F = net force, m = mass, a = acceleration
• The SI unit of the force is Newton.​​

Newton's Second Law of motion:

• Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration
• Formula, Force, F=dPdtF=dPdtF=dPdt

, where dP = change in momentum, dt = change in time.

• Force, F = ma, where m = mass, a = acceleration
• It is applied to identify the amount of force needed to make an object move or make it stop.

Calculation:

Given,

The mass of the engine, M = 10000 kg

The mass of each 5 wagons, m = 2000 kg

The force exerted by the engine, F =  45000 N

Frictional force, f = 5000 N

Net force, F_net = ma

Fnet = F - friction force

Fnet = 45000 - 5000 = 40000 N

According to Newton's second law,  Fnet = ma, here, m = total mass

Fnet = (M + 5m) a

\(a=\frac{F_{net}}{M+5m}\)

\(a=\frac{40000}{10000+5\times 2000}\)

a = 2 m/s²

Concept:

Universal Gravitational Law:

• Sir Isaac Newton put forward the universal law of gravitation in 1687 and used it to explain the observed motions of the planets and moons.

• Newton’s Law of Universal Gravitation states that every particle attracts every other particle in the universe with force directly proportional to the product of the masses and inversely proportional to the square of the distance between them.

• Formula, Force, \(F=\frac{GM_1M_2}{r^2}\)where, F is the gravitational force between bodies, M₁ and M₂ are the masses of the bodies, r is the distance between the centers of two bodies, and 8G is the universal gravitational constant.

• Here, G = 6.673 x 10-11 N m2/kg2.

​Acceleration due to gravity:

• Acceleration due to gravity is the acceleration gained by an object due to gravitational force.
• Its SI unit is m/s². It has both magnitude and direction, hence, it’s a vector quantity.
• Acceleration due to gravity is represented by g.
• The standard value of g on the surface of the earth at sea level is 9.8 m/s².

Explanation:

Gravitational force, \(F=\frac{GM_1M_2}{r^2}\)

\(G=\frac{Fr^2}{M_1M_2}\)

The SI unit of the universal gravitational constant is N m²/kg².

The SI unit of the acceleration due to gravity is the same as that of acceleration. Hence, the SI unit of the acceleration due to gravity is m/s².

Concept:

Motion:

• Motion is the phenomenon in which an object changes its position.
• Motion is represented in terms of displacement, distance, velocity, acceleration, speed, and time

​Equation of motion: 

• v = u + at
• S = ut + 0.5 at²
• 2as = v² - u²
• Here, v = final velocity, u = initial velocity, a = acceleration, t = time
• Under the influence of gravity, acceleration is replaced by the acceleration due to gravity.

Calculation:

Given,

The initial velocity, u = 20 m/s, The final velocity, v = 0 m/s, The acceleration due to gravity, g = 10 m/s²

From the third equation of motion under the influence of gravity,

v² - u² = -2gh

\(h=\frac{v^2-u^2}{-2g}\)

\(h=\frac{0^2-20^2}{-2\times 10}=20~m\)

Hence, the maximum height is 20 m.

Concept:

Density:

• It is defined as the mass per unit volume.
• Formula, Density, \(ρ=\frac{m}{V}\), where m = mass, V = volume
• The SI unit of density is kg/m³.

Relative density:

• The difference between the specific gravity and density is that at room temperature and pressure, 1gram per 1 cubic cm is the density of water this density is treated as a standard and the density of any other material (usual liquids) is calculated relative to this is called relative density or specific gravity.
• Formula, \(R.D=\frac{ρ_l}{ρ_w}\), where, R.D = relative density, ρ_l = density of water, ρ_w = density of water

Calculation:

Given, the weight of an object in air = W_a

When an object is immersed in water, then W_w = W_a - ρ_w gV

ρw gV  = Wa - W_w . . . . . . . . .(1)

When an object is immersed in liquid, then, W_l = W_a - ρ_l gV 

ρl gV = Wa -  Wl  . . . . . . . . . .(2)

Divide equation (2) by equation (1), we get the relative density

\(\frac{ρ_l}{ρ _w}=\frac{W_a-W_l}{W_a-W_w}\)

Concept:

Energy:

• It is defined as energy as the ability of something to do work.
• Energy can exist in many forms.
• All forms of energy are either kinetic or potential.
• The International System of Units of measurement of energy is the joule.
• The unit of energy is named after James Prescott Joule. Joule is a derived unit equal to the energy expended in applying a force of one newton through a distance of one meter.
• However, energy is also expressed in many other units not part of the SI, such as ergs, calories, British Thermal Units, kilowatt-hours, and kilocalories, which require a conversion factor when expressed in SI units.

​Energy in terms of power:

• Power is defined as the energy per unit of time.
• Formula, Power, \(P =\frac{E}{t}\), where E = energy, t = time
• Hence, E = Pt

Explanation:

The SI unit of energy is Joule.

We can derive the SI unit of the energy from the formula of potential energy.

P.E = mgh =(mg) h

Hence, the SI unit is Nm.

Energy, E = Pt, where, P = power, t = time, 

So, the SI unit of power is the watt. Therefore, the SI unit of energy is Watt hour or kilowatt hour. Here kilo means 1000.

Concept:

• The relation between kinetic energy and momentum is given as, \(K.E =\frac{P^2}{2m}\) where P = momentum, m = mass

Kinetic energy:

• The energy possessed due to the motion of an object is called kinetic energy.
• Formula, Kinetic energy, \(K.E=\frac{1}{2}mv^2\) where m = mass, v = velocity
• The SI unit of kinetic energy is Joules (J).

Momentum:

• It is defined as the product of mass and velocity.
• Formula, P = mv, where m = mass, v = velocity, P = momentum
• The SI unit of the momentum is kg m/s.The

Calculation:

Given,

The momentum of an object, K.E = 72 J

The mass of the object, m = 1 kg

The kinetic energy of the bullet is calculated as,

\(K.E= \frac{P^2}{2m} \)

\(P=\sqrt{2m(K.E)} \)

\(P=\sqrt{2\times 1 \times 72}= 12 ~kg, m/s\)

Hence, the momentum of an object is 12 kg m/s.

Concept:

Frequency:

• The frequency (f) of a wave is the number of full waveforms generated per second.
• This is the same as the number of repetitions per second or the number of oscillations per second.

Time period:

• ​Time Period (T) is the number of seconds per waveform or the number of seconds per oscillation.
• It is clear that frequency and period are reciprocals.

Wavelength: 

• Wavelength (λ) is the distance between two successive points on a wave that is in the same state of oscillation.
• The wavelength of the wave can be calculated as, λ = vT, where, v = velocity, T = time period

Calculation:

Given, speed, v = 1200 m/s

The time period of the one wave, T = 2 μs

The wavelength of the wave can be calculated as, λ = vT

 λ = 1200 × 2 × 10^-6

λ  = 2.4 × 10^-3 m

Hence, the wavelength of the wave is 2.4 × 10-3 m.

Correct answer: 1)

Concept:

• A disease that is simply by breathing is called airborne disease.
• The airborne disease can spread when people sneeze, or talk and cough spewing nasal and throat secretions into the air.
• Some viruses or bacteria take flight and hang in the air on other people or surfaces.

Explanation:

• Airborne diseases spread through the medium of air in the form of sneeze and cough droplets, which when inhaled by a healthy person may cause the disease.
• These can be transmitted easily in an overcrowded room.
• Thus, overcrowding should be avoided to prevent air-borne diseases.

Conclusion:

Thus, people living in an overcrowded and poorly ventilated houses are likely to suffer from Airborne diseases.

Important Points

• Viruses are very minute infectious agents.
• Viruses  consists of a single molecule of nucleic acid that is surrounded by a protein coat, the capsid.
• They lack the protoplasm.
• Therefore they are considered dead outside.
• They transform into living organisms once they enter a host body.
• Viruses depend on the host cell machinery for their replication.
• They do not possess the required ribosomes and so, cannot independently form proteins from molecules of messenger RNA.
• Due of these reasons, viruses can replicate only within a living host cell.

Explanation:

• Most of the antibacterial drugs target by commonly blocking the biochemical pathways important for bacteria.
• But in viruses this is not possible because viruses have very few biochemical mechanisms of their own.
• Viruses lack cellular machinery and hence do not show any characteristics of life until they enter a living body/host and use the host cell to multiply.
• Thus, any it becomes very difficult to prepare an antiviral drug having particular mode of action.

Important Points

• Ozone is an odorless and colorless gas that is is a natural part of the environment.
• It is made up of three oxygen molecules (O₃).
• Most ozone (about 90%) is found in the stratosphere.
• In the upper atmosphere, the layer of ozone gas helps in protecting the earth from the sun's UV radiation.
• But, on ground level, ozone acts as a harmful air pollutant.
• It is harmful if a person inhales it, may lead to lung and throat irritation, coughing, and worsened asthma symptoms.

Explanation:

• Ozone hole is the region where ozone is depleted.
• It is actually a region of exceptionally depleted ozone in the stratosphere (mainly over the Antarctica).
• Usage of gases like chlorofluorocarbons (CFCs) in spray cans and refrigerants, leads to breakdown of ozone molecules in the upper atmosphere.
• This causes thinning of the ozone layer.
• The chlorine and bromine gases produced from CFCs and halons are responsible for the destruction of ozone molecules.
• Ozone depletion may lead to increased amounts of UV radiation to reach the Earth.
• This can lead to more cases of skin cancer, cataracts, and impaired immune systems.

Additional Information

Montreal Protocol - 

• It was signed in 1987 in Montreal, Canada for the protection of Ozone layer in the atmosphere.
• Developing and developed countries have equal but differentiated responsibilities under this protocol.
• The Kigali Amendment, an amendment to the Protocol, has helped reduce HFC emissions.

Important Points

• Apiculture - the scientific method of rearing honeybees in order to obtain bee products such as beeswax, honey, royal jelly, flower pollen, and bee pollen.
• Apiculture or bee-keeping is the practice of scientific maintenance of honeybee colonies, commonly in hives, by humans.
• And then collection of these bee products and marketing them professionally
• Bees are economically important, social and colonial insects.
• They are used majorly for production of honey and wax commercially.

Explanation:

• Apis mellifera is a species of honey bee that is commonly used for commercial honey production.
• They are reared because of the high amount of honey production.
• It is an Italian bee species.
• In India, Apis indica is widely used for rearing.

Additional Information

• A honey bee colony consists of three kinds of adult bees:
• workers
• drones
• queen
• The workers and the queen are female, while the drones are male.
• Honey bee colonies only have a single queen and its primary duty is to lay eggs.

Correct answer: 2)

Concept:

• When magnesium strip is burnt, then ash obtained is MgO which is when dissolved in water then Mg(OH)₂ is formed.
• Mg(OH)₂ is basic in nature as it turns red litmus to blue.
• The burning magnesium ribbon in air is a direct combination reaction.
• The formation of magnesium oxide is a chemical change.

Explanation:

• The magnesium ribbon reacts with oxygen to form magnesium oxide.
• This is an example of oxidation reaction.
• Magnesium ribbon bums with a dazzling white light and produces a white powder which is magnesium oxide.
• The reaction can be represented as
• 2Mg + O₂ →2MgO

Conclusion:

Thus, when a student burns a magnesium ribbon on a bunsen flame and collects the ash formed on a watch-glass and the ribbon burns with a brilliant white light.

Correct answer: 3)

Concept:

• The type of reaction in which part of one reactant is displaced by another reactant is called displacement reaction.
• It is also called a  replacement reaction.
• As replacement of one ion of reactant takes place by another ion of reactant.

Explanation:

• Copper can not displace iron from ferrous sulphate solution.
• So no change will take place.
• Copper being less reactive than iron is placed at the bottom of the reactivity series, below the iron.
• Therefore, a displacement reaction does not take place as copper cannot displace iron from an iron sulphate solution.
• Cu(s) + FeSO₄(aq)→ No reaction.

Conclusion:

Thus, the solution remains green and no change takes place in the copper plate.

Correct answer: 1)

Concept:

• Oxidation is the loss of electrons while reduction is the gain of electrons.
• The substance which helps other species to get reduced and itself get oxidized is known as a reducing agent.
• While substance that helps other species to get oxidized and itself get reduced is known as oxidizing agent

Explanation:

• In this reaction, HCl is oxidized to Cl2, and MnO2 is reduced to MnCl2
• Reactant side, the oxidation number of Mn is +4
• Oxidation number of O is -2
• Oxidation number of H is +1
• Oxidation number of Cl is -1
• Product side, the oxidation number of Mn is +2
• Oxidation number of O is -2
• Oxidation number of H is +1
• Oxidation number of Cl is 0.
• So, HCl is oxidised to Cl2 and MnO2 is reduced to MnCl2

Conclusion:

Thus, HCl is oxidised to Cl2 and MnO2 is reduced to MnCl2

Correct answer: 2)

Concept:

• Oxygen cannot be used as it is an oxidizing agent. Helium can be used as it is an inert gas.
• Nitrogen is less reactive and it is cheaper than Helium.
• In most cases, nitrogen is used in packets to prevent rancidity.
• Rancidity is the oxidative degradation of oil. We can avoid the rancidity of oil if we can avoid contact between oil and air.
• Due to the rancidification process of oils and fats, you will observe change in colour, smell, and test.
• For example, if you expose a packet of chips to air, we will observe a change in smell and taste.
• During rancidification, oils and fats undergo complete oxidation or hydrolysis.

Explanation:

• Helium, as well as nitrogen, can be used for storage of a fresh sample of oil for a long time because they abstain from the oil from rancidity.
• The contact of air and oil is prevented by using nitrogen or helium as blanketing gas.
• Both are non-reactive at standard temperature and pressure.
• There is no oxygen (or air ) to cause its oxidation and make it rancid.

Conclusion:

Thus, the gases which can be used for the storage of fresh samples of oil for a long time are nitrogen and helium.

Correct answer: 4)

Concept:

• The boiling point is the point when the substance starts to boil.
• The miscible liquids are those which are completely mixed with each other and form a homogeneous solution but the liquids have sufficient boiling point difference.

Explanation:

• In option (1), Centrifugation is the process that uses centrifugal force for the separation of two liquids in a mixture.
• In this process, the denser component of the mixture migrates away from the axis and the lighter component migrates toward the axis.
• In option (2), Distillation is the process that occurs when a liquid sample is volatilized to produce a vapor that is subsequently condensed to a liquid richer in the more volatile components of the original sample.
• In option (3), A separating funnel is a funnel that is used to separate immiscible liquids.
• Liquids that do not mix with each other are said to be immiscible.
• In option (4), the term fractional distillation is a method to separate two completely mixed liquids having a temperature difference of more than 25K.
• So the given liquids have a boiling point difference of less than 25K and are separated by fractional distillation.

 

Conclusion:

Thus, the two miscible liquids having boiling points of 132°C and 150°C can be separated by fractional distillation.

Correct answer: 4)

Concept:

• The meaning of hydrogen ion concentration is the concentration of hydrogen ions in a solution, usually in moles per liter or in pH units.
• Hydrogen ion concentration is more conveniently expressed as pH, which is the logarithm of the reciprocal of the hydrogen ion concentration in gram moles per liter.

Explanation:

• Acidity is a measure of the concentration of hydrogen ions (H^⁺) present when a substance is dissolved in a liquid.
• Propionic acid is more acidic than all others because the anion of  acid is resonance stabilized
• Propionic acid (C₂H₅COOH ​) is the most acidic substance among the following.
• Thus, it has the highest amount of hydrogen ions.

Conclusion:

Thus, C2H5COOH would have the maximum concentration of hydrogen ions.

Correct answer: 3)

Concept:

• A thermite reaction is a broad term describing an exothermic reaction between ferrous oxides and aluminum.
• The thermite process is the reduction of metal oxides with aluminum powder in which a huge amount of heat is liberated is called thermite process.
• This aluminum-iron oxide combination, often known as thermite, is well recognized for its capacity to create high heat upon burning.

Explanation:

• When highly reactive metals such as Sodium (Na), Calcium(Ca), Aluminium(Al), etc., are used as reducing agents they displace metals of lower reactivity from the compound.
• Fe₂O₃ (s) + 2 Al (s) → 2 Fe (l) + Al₂O₃ (s) + heat
• These are exothermic reactions.
• The amount of heat evolved is so large that the metals are produced in the molten state.
• Iron oxide reacts with aluminum to join the railing of railway tracks or cracked machine parts.
• This reaction is known as the thermite reaction.

Conclusion:

Thus, Fe2O3 (s) + 2 Al (s) → 2 Fe (l) + Al2O3 (s) + heat, is a thermite reaction.

Correct answer: 4)

Concept:

• Group 1 elements are Li, Na, K, Rb, Cs, and Fr.
• The third period contains eight elements: sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, and argon.
• Solutions in which water is the solvent are called aqueous solutions.
• Sodium chloride (NaCl) and water (H₂O) solution are brine solutions.
• The brine is used in electrolysis.

Explanation:

• Group 1 elements like lithium, sodium, and potassium all react vigorously with water.
• Alkali metals need to be stored under oil to prevent them from reacting with the oxygen and water vapor in the air.
• Sodium and chlorine combine to form sodium chloride.
• 2Na + Cl₂ → 2NaCl
• Brine is an aqueous solution of NaCl (Sodium Chloride).
• sodium (Na), the chemical element of the periodic table's alkali metal (Group 1 and third period).

Conclusion:

Thus, this metal belongs to the third period and the first group in the Modern Periodic Table.

Correct answer: 4)

Concept:

• Metal oxides are basic in nature hence they give an alkaline solution when dissolved in water.
• During these reactions, a large amount of energy gets released.
• Gold generally does not react with oxygen, water, and acid.

Explanation:

• All metal oxides react with water to give salt and acid is the incorrect statement.
• As all metal oxides react with water to give a base.
• CaO + H₂O→ Ca(OH)₂
• Some non-metal oxides react with water to form acids.
• CO₂ + H₂O→ H₂CO₃
• Some of the metals react with acids to give salt and hydrogen gas.
• Mg + 2HCl → MgCl₂ +H₂
• All metal carbonates react with acids to give salt, carbon dioxide, and water.
• Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂

Conclusion:

Thus, B, C, and D are the correct statements.

Correct answer: 4

Concept:

• Compounds that have the same molecular formula but different chemical structures are called isomers.
• That excludes any different arrangements which are simply due to the molecule rotating as a whole, or rotating about particular bonds.

Explanation:

• An isomer contains the same number of atoms of each element but has different arrangements of their atoms.
• Isomers contain the same number of atoms of each element but have different arrangements of their atoms.
• Isomers do not necessarily share similar properties unless they also have the same functional groups.
• In compound A, the molecular formula is C₆H₁₂ but have a different structure. So they are isomers.
• In compound B, the molecular formula is C₄H₁₀ but has a different structure. So they are isomers.
• In compound C, the molecular formula is C₄H₁₀ but its structure has only 8 hydrogens. So they are not isomers.
• In compound D, the diffrent molecular formula is C₅H₁₂ but have a different structure. So they are isomers.

Conclusion:

Thus, options A, B, and D depict the same molecular formula but different structural formulas.