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The correct answer is Alkanes.

Key Points

• Alkanes group was given the name ‘paraffin’.
• Paraffins, also known as alkanes, are saturated compounds that have the general formula CnH_2n+2, where n is the number of carbon atoms.
• The simplest alkane is methane (CH₄), which is also represented as C₁.
• Alkanes are called paraffin because they have a little affinity towards a general reagent. In other words, alkanes are inert substances.
• Paraffin wax was first produced commercially in 1867, less than 10 years after the first petroleum well was drilled.

Additional Information

• In organic chemistry, an aldehyde is an organic compound containing a functional group with the structure R−CH=O.
• The common names of aldehydes are taken from the names of the corresponding carboxylic acids: formaldehyde, acetaldehyde, and so on
• Alcohol is an organic compound with a hydroxyl (OH) functional group on an aliphatic carbon atom.
• OH is the functional group of all alcohols, we often represent alcohols by the general formula ROH, where R is an alkyl group.
• The word acid is derived from the Latin acidus/acēre, meaning 'sour'.
• There are two basic types of acids organic and inorganic acids. Inorganic acids are sometimes referred to as mineral acids.

घबराहट में प्रयुक्त प्रत्यय है आहट । 

Key Points

• आहट यहाँ सही विकल्प है, अन्य विकल्प असंगत है।
• घबराहट में पीछे आहट प्रत्यय लग रहा है।
• अत: सही विकल्प आहट ही होगा।

Additional Information

• प्रत्यय - वे शब्द जो किसी शब्द के पीछे लगकर उसका सार्थक अर्थ बना देते है, प्रत्यय कहलाते है।
• जैसे- घबरा + आहट = घबराहट
• समाज + इक = सामजिक

Given:

The perimeter of a circle is P. 

Formula used:

The perimeter of a circle = 2πr

Calculation:

The perimeter of a circle = 2πr = P

⇒ r = P/2π 

According to the question,

Radius = 2r

Now, 

The new perimeter = 2π × 2r

⇒ 2π × 2 × P/2π 

⇒ 2P

∴ The new perimeter will be 2P.

Correct option is 2 which is N_2.

• A chemical symbol is a one- or two-letter designation of an element.
• Some examples of chemical symbols are O for oxygen, Zn for zinc, and Fe for iron. The first letter of a symbol is always capitalized.
• If the symbol contains two letters, the second letter is lowercase.

Explanation:

• The chemical formula of Nitrogen is N but Nitrogen exists in a molecule of two ions hence the chemical symbol of Nitrogen gas is written as N₂.

• The symbol of nitrogen is only N. N₂ is the formula of the nitrogen molecule, which has two atoms of nitrogen in it. The nitrogen gas exists only as N₂ molecules in free state.

• The chemical formula for nitrogen gas is N₂.

• Nitrogen gas is one of the diatomic elements, in which one molecule consists of two atoms of the same element bonded by one or more covalent bonds. In the case of N₂, the two nitrogen atoms are bonded by a triple covalent bond.

• One of the diatomic elements is nitrogen gas, which is made up of two atoms of the same element joined by one or more covalent bonds.

 Two atoms of the element join together at ordinary temperature and pressure to generate dinitrogen, a colourless and odourless diatomic gas with the formula N₂.

The correct answer is Gold.

Key Points

• Metals are lustrous, elastic, and malleable.
• Metals are good conductors of heat and electricity
• Tensile is the ability of a metal to be drawn in wire form.
• Gold is the most ductile metal.
• A wire of about 2 km in length can be drawn from one gram of Gold.
• The metal which is neither ductile nor malleable is zinc.
• Mercury and gallium are found in a liquid state at room temperature.
• Silver is the most conductive metal.

Given:

The average weight of 21 workers is 45 kg

If weight of the manager is included, the average increases by 3 kg

Formula Used:

Average = Sum of all Observations/Number of Observations

Calculation:

Sum of weights of workers = 45 × 21 = 945 kg

Let the weight of the manager be x kg

According to the question,

45 + 3 = (945 + x)/22

⇒ 48 × 22 = 945 + x

⇒ x = 1056 - 945 = 111

∴ The weight of the manager is 111 kg.

Shortcut TrickLet the weight of manager = N

N = Old average + Increased average × No. of persons(including the new member)

⇒ N = 45 + 3 × 22 = 45 + 66 = 111 kg

∴ The weight of the manager is 111 kg.

The correct answer is- '(A).'

Key Points

• The error lies in Part (A) of the sentence.
• Countable nouns, as the term suggests, refer to things that can be counted.
• They have singular and plural forms.
• Example: table, tables; month, months; pen, pens, etc.
• Uncountable nouns cannot be counted.
• They have a singular form and do not have a plural form.
• Example: dirt, rice, information, furniture, charity, hair, etc.
• Therefore, the use of 'Charity begin' should be replaced by 'Charity begins' to make it grammatically correct.
• Hence, the correct answer is '(A).'
• Correct sentence: Charity begins at home, but should not end there.

Additional Information 

• Countable nouns, as the term suggests, refer to things that can be counted.
• They have singular and plural forms.
• Example: table, tables; month, months; pen, pens.
• Uncountable nouns cannot be counted.
• They have a singular form and do not have a plural form.
• Example: dirt, rice, information, furniture, and hair.

 Hinglish 

• त्रुटि वाक्य के Part (A) में है।
• Countable nouns, जैसा कि शब्द से पता चलता है, उन चीजों को संदर्भित करती हैं जिन्हें गिना जा सकता है।
• उनके singular और plural रूप हैं।
• Example: table, tables; month, months; pen, pens, etc.
• Uncountable nouns की गणना नहीं की जा सकती।
• उनका singular रूप है और plural रूप नहीं है।
• Example: dirt, rice, information, furniture, charity, hair, etc.
• इसलिए वाक्य में  'Charity begin' के प्रयोग को 'Charity begins' से बदल देना चाहिए ताकि वह व्याकरण की दृष्टि से सही हो।​

Detailed Video Concept

A lever is a rigid rod which rotates about a fixed point called the fulcrum.

All levers are functioning on the following principle:

Load × Load arm = Effort × Effort arm

The distance of the load from the fulcrum is called load arm and the distance of the effort from the fulcrum is called effort arm.

Straight levers are classified as:

The correct answer is 'Option 3'.

Key Points

• Here, Nita's experience of having heard the podcast before is still a relevant fact when she is reporting it, so the present perfect tense ("has heard") will be retained in the reported speech.
• When the Direct Speech is in Present Tense (in this case, 'says') or Future Tense, there is no change in the Indirect Speech.
• 'Has' will be used instead of 'Have' as we use 'Has' with singular noun or singular pronoun.

Therefore, the correct sentence is: 'Nita says that she has heard the podcast before.'

Additional Information

• Let's look at the other options:
• "Nita says that she is hearing the podcast before." : This is incorrect because "is hearing" is present continuous tense, which doesn't fit the meaning of the sentence, and "before" can't be used with this tense in this context.
• "Nita says that she had heard the podcast before." : This is not incorrect, but it's more common to use "has heard" in this context for the reasons explained above.
• "Nita says that she had heard the podcast ago." : This is incorrect because "ago" is not used with the past perfect tense. It's used with the past simple tense to indicate how much time has passed since an event. Also, the word "before" is missing from the sentence.

The correct answer is Gwalior.

• The Indian Mutiny of 1857 effectively ended in the city of Gwalior.

Key Points

• The Indian Mutiny of 1857 was a major revolt in India in 1857–58 against the rule of the British East India Company, which acted as a sovereign power on behalf of the British Crown.
• The rebellion began on 10 May 1857 as a mutiny by soldiers of the Company's army in the garrison town of Meerut.
• The rebellion posed a great threat to British power in that region and was only contained with the defeat of the rebels at Gwalior on 20 June 1858.
• Its name has been contested and has been described as the Sepoy Mutiny, the Indian Rebellion, the Great Rebellion, the Rebellion of 1857, the Indian Rebellion, and the First War of Independence.

Additional Information