Mathematics and Science PYQs

The correct option is:4) Both (A) and (R) are false.

Concept:

Digestion:

• The process of conversion of complex food substances to simple absorbable forms is called digestion and is carried out by our digestive system through mechanical and biochemical methods
• The digestion is performed in the following manner
• Mouth – Oesophagus – Stomach – Small intestine – Large intestine

Explanation:

• Assertion (A) is false. Carnivores, like tigers, actually have a shorter small intestine compared to herbivores. This is because meat is easier to digest than plant matter, particularly cellulose, which requires a longer digestive tract and more time to break down.
• Reason (R) is also false. Meat is not more difficult to digest than cellulose. In fact, cellulose is one of the most difficult substances for many animals to digest. Ruminants like cows and sheep have specialized stomachs with multiple compartments and symbiotic bacteria to help them digest cellulose, while many animals (including humans) can't digest it at all.

The correct answer is Acids have a pH value of less than 7.

Concept;

Acids

• Acids are molecules that are capable of giving H+ ions or forming a covalent bond with electrons.
• pairs. Acids are sour in taste.
• Blue litmus turns red when brought in the presence of acid and does not change color in the presence of a base.
• Acids are naturally present in citrus fruits like oranges, grapes, etc.
• The pH of acids is below 7.

Bases

• Bases are bitter in taste and have a soapy feel.
• Red litmus turns blue in the presence of a base and does not change in the presence of acid.
• Baking soda, neem, clove, etc are examples of bases.
• The pH range of bases falls above 7

 

Explanation:

• Acids are bitter in taste: This statement is incorrect. Acids are generally sour in taste, not bitter. For example, substances like lemon juice and vinegar are sour and acidic.
• Acids have a pH value of less than 7: This statement is correct. The pH scale is a measure of the acidity or alkalinity of a solution. A pH value of less than 7 indicates acidity.
• Acids have pH values below 7, with lower values indicating stronger acidity.
• Acids turn red litmus blue: This statement is incorrect. Acids do not turn red litmus paper blue.
• Acids turn blue litmus paper red. Blue litmus paper is used as an indicator to test for the presence of an acid.
• If the blue litmus paper turns red when it comes into contact with a substance, it indicates the presence of an acid.
• Acids give a reddish-brown color with turmeric: This statement is incorrect. Acids do not give a reddish-brown color with turmeric.
• Turmeric is often used as an indicator to test for the presence of bases. It turns reddish-brown in the presence of bases, not acids .

The correct answer is Calcium, osteoporosis, dairy products. 

Explanation:

• Calcium is a vital mineral required by our body to build strong bones and teeth.
• Calcium plays a crucial role in maintaining bone health and is necessary for various physiological functions.
• Osteoporosis is a condition characterized by the loss of bone density and strength, making bones fragile and more susceptible to fractures.
• We are at an increased risk of osteoporosis if we do not get enough calcium.
• Dairy products are a rich source of calcium. Examples of dairy products include milk, cheese, and yogurt, which are commonly known for their high calcium content.
• They are often recommended as a source of calcium to meet the body's requirements.

The correct answer is Increase in wind speed.

Concept:

• Evaporation: The process by which liquid substances are converted into their vapor form is called evaporation. Ex - Water(liquid) gets evaporated to form water vapours (gas)

Explanation:

• The rate of evaporation is affected by several factors like Surface area, temperature, humidity & wind speed

Surface Area:

• The rate of evaporation is directly proportional to the surface area i.e the bigger the surface area is more molecules will escape into the atmosphere
• This can be understood as if a liquid is kept in two different vessels - in a test tube and in a china dish, then the liquid kept in the beaker will evaporate faster compared to the liquid kept in the test tube because the china dish a larger surface area than the test-tube

Other factors that affect the rate of Evaporation:

• Increase in humidity: This option is incorrect. Higher humidity means there is already a high amount of moisture present in the air.
• When the air is saturated with water vapor, the rate of evaporation decreases.
• Therefore, an increase in humidity reduces the rate of evaporation.
• Increase in wind speed: This option is correct. When wind speed increases, it enhances the movement of air molecules over the surface of the water.
• This increased movement helps in carrying away the water vapor that is evaporating from the surface, resulting in a higher rate of evaporation.
• Decrease in temperature: This option is incorrect. Temperature is a crucial factor affecting the rate of evaporation. As the temperature increases,
• The energy of water molecules increases, leading to a higher rate of evaporation. Conversely, a decrease in temperature lowers the energy of water molecules, resulting in a slower rate of evaporation.

The correct answer is (A) and (C).

Concept:

Physical change:

• Properties such as shape, size, color, and state of a substance are called its physical properties.
• A change in which a substance undergoes a change in its physical properties is called a physical change.
• A physical change is generally reversible. In such a change no new substance is formed.
• Freezing of water, Mixing of iron filings and sand is a physical change as no new substance is formed and the change is reversible.

Chemical Change:

• A change in which one or more new substances are formed is called a chemical change.
• A chemical change is also called a chemical reaction.
• A chemical change is generally irreversible.
• Growth of a plant, Rusting of iron, Cooking of food, Burning of a candle, etc. are all chemical changes as these are irreversible.

Explanation:

• Rusting of iron is a chemical and irreversible change: This statement is correct. Rusting is a chemical process that occurs when iron reacts with oxygen in the presence of water or moisture.
• It results in the formation of a new substance called iron oxide, commonly known as rust. Rusting is an irreversible change because once iron has rusted, it cannot be easily converted back to its original form without undergoing a separate chemical process.
• Melting of ice is a chemical and reversible change: This statement is incorrect. The melting of ice is a physical change, not a chemical change.
• It is a phase change in which solid ice converts into liquid water. It does not involve the formation of new substances with different chemical properties.
• Melting is a reversible change because if the melted water is cooled, it can freeze again to form ice.
• Breaking a piece of glass into pieces is a physical and irreversible change: This statement is correct. Breaking a piece of glass is a physical change.
• It involves the physical separation of the glass into smaller pieces due to the application of force.
• Breaking glass does not involve a change in the chemical composition or the formation of new substances.
• Once the glass is broken into pieces, it cannot be easily reassembled to its original form, making it an irreversible change.

The correct answer is Only (B)

Explanation:

• When a lemon is dropped into ordinary tap water and it sinks to the bottom, it indicates that the density of the lemon is greater than the density of water.
• In order to make the lemon float, we need to increase the buoyant force acting on the lemon.
• By adding salt to the water, the density of the water increases. Salt, when dissolved in water, forms ions that increase the mass of the water without significantly changing its volume. As a result, the density of the saltwater solution increases.
• When the density of the saltwater solution becomes greater than the density of the lemon, the buoyant force acting on the lemon increases.
• The buoyant force is the upward force exerted by a fluid on an object immersed in it.
• It is equal to the weight of the fluid displaced by the object. If the buoyant force becomes greater than the weight of the lemon, the lemon will experience a net upward force and will float.
• Adding more water to the container will not change the density of the water. Therefore, it will not be helpful in making the lemon float.

The correct answer is 7 m

Concept:

• When a person moves closer to a plane mirror, the distance between the person's image and the person decreases by twice the distance the person moves.

Calculation:

The initial distance between the person and the image = 13 m

Distance person moves = 3 m

According to the principle mentioned earlier, the distance between the person's image and the person will decrease by twice the distance the person moves.

New distance = Initial distance - (2 * Distance person moves)

New distance = 13 m - (2 * 3 m) =  13 m - 6 m = 7 m

New distance = 7 m

The correct option is: 3) (A) is true but (R) is false.

Concept:

• A good conductor of electricity is a material that allows electric current to flow through it with minimal resistance.
• It is characterized by having a high electrical conductivity. In a good conductor, the outermost electrons of the atoms are loosely bound and are free to move within the material.
• These free electrons can easily carry electric charges, allowing the flow of electric current.
• Metals, such as copper, silver, aluminum, and gold, are known for their high electrical conductivity and are commonly used as conductors in electrical wiring, circuitry, and various electrical components.

Explanation:

• Assertion (A) is true because copper is indeed a good conductor of electricity. This is due to the structure of its atoms, which allows free electrons to move easily, facilitating the flow of electricity.
• However, Reason (R) is false. It's not true that all good conductors of heat are good conductors of electricity.

Some materials, like ceramics, can conduct heat well but are poor electrical conductors. The conduction of heat and electricity are related properties, but they don't always coincide.

The correct answer is Sperm, ovum, zygote, embryo.

Explanation:

• In the female reproductive system, the female produces eggs whereas the male has sperm. When they fuse to form a zygote.
• Which after fertilization converts into an embryo.
• Gamete: The gamete is also termed reproductive/sex cells. The female gamete is called ova/egg cells whereas the male gamete is sperm.
• Embryo: It is the early-stage development of the unborn baby of the multicellular organism.
• Egg: It is a female reproductive cell or ovaries, this is the part of the gamete.
• Ovum: Female reproductive cells ovum (singular) or ovaries (plural). When this fuse to sperms forms a zygote.
• Out of these four gametes (Ovum/egg + sperm), Egg and Ovum are the same in meaning whereas the Embryo is the later developed process.

The correct answer is In these areas, no tourism is permitted.

Key Points

• The biosphere reserves are the areas meant for the conservation of biodiversity.
• These are large areas of protected land for the conservation of wildlife, plant and animal resources, and the traditional life of the tribals living in the area.
• The biosphere reserves help to maintain the biodiversity and culture of that area.
• A biosphere reserve may also contain other protected areas.

Explanation:

• Biosphere reserves have no fixed boundaries: Biosphere reserves typically have zonation, which means they consist of different zones with varying levels of protection and human activity.
• These zones include a core area, a buffer zone, and a transition area.
• The core area has the highest level of protection, while the buffer zone allows limited human activity, and the transition area facilitates sustainable development.
• Although the exact boundaries may vary, biosphere reserves do have defined zones**.**
• In these areas, no tourism is permitted: This statement is incorrect. Biosphere reserves often encourage sustainable tourism as a means to generate income and promote awareness about conservation.
• However, tourism activities within biosphere reserves are carefully regulated to minimize their impact on the environment.
• **These areas are aimed at the conservation of biodiversity: **This statement is correct. Biosphere reserves are established with the primary objective of conserving biodiversity.
• They serve as living laboratories for studying and understanding ecosystems, promoting sustainable land and resource management, and maintaining ecological balance.
• They are spread over a large area: This statement is generally correct. Biosphere reserves are typically spread over a large area, encompassing various ecosystems and habitats.
• The large size allows for the conservation of diverse species and ecosystems, facilitating the protection of biodiversity at a broader scale.

Engaging students in hands-on push and pull activities is an effective way to introduce the concept of force in a class VI setting.

Key Points

• By participating in these activities, students can directly experience the application of force and understand its effects on objects.
• Through pushing and pulling objects of different sizes and weights, students can observe how force influences the motion and behavior of those objects.
• This approach promotes active learning, encourages students to make observations, and allows them to explore the concept of force in a tangible and experiential manner.
• It lays the foundation for further discussions and explanations about force, its properties, and its relationship to other concepts in physics.

Hence, it can be concluded that option 4 is the correct answer.

The original statement highlights the concept of falsifiability as the ultimate criterion that distinguishes science from pseudoscience.

Key Points

• Falsifiability refers to the capacity of a scientific theory to be tested and potentially proven incorrect or false.
• It emphasizes that scientific theories are subject to scrutiny, experimentation, and empirical evidence, allowing for the possibility of refutation or revision based on the outcomes of testing.
• This characteristic distinguishes science from pseudoscience, where claims often lack the capacity for falsification or verification through empirical means.

Hence, it can be concluded that option 3 is the correct answer.

Laboratory activities play a crucial role in science education by providing students with opportunities to apply theoretical concepts in a practical setting.

Key Points

• Through hands-on experimentation and observation, students can directly engage with scientific phenomena, collect data, analyze results, and draw conclusions.
• This process helps students deepen their understanding of scientific concepts and principles by connecting them with real-world applications.
• Laboratory activities foster critical thinking, problem-solving skills, and scientific inquiry.
• They encourage students to make connections between theory and practice, bridging the gap between abstract concepts and their practical implications.
• By actively participating in laboratory work, students develop a deeper appreciation for the practical aspects of science and gain a more holistic understanding of the subject.

Hence, it can be concluded that option 3 is the correct answer.

A scientific theory represents a comprehensive framework that provides understanding and explanation for a specific aspect of the natural world.

Key Points

• It is not a mere guess, but rather an explanation that is supported by a substantial body of evidence, empirical data, and logical reasoning.
• Scientific theories are developed through rigorous scientific investigation, experimentation, and analysis.
• They go beyond individual observations and describe the underlying mechanisms and principles that govern a particular phenomenon.
• Scientific theories are subjected to scrutiny and testing, and they may evolve and adapt as new evidence emerges.
• However, they are considered reliable and widely accepted explanations that can make accurate predictions and provide a basis for further scientific exploration.

Hence, it can be concluded that option 2 is the correct answer.

In this experiment, the teacher instructed the students to vary the factor of interest, which is the temperature, while keeping the other factors constant across situations.

Key Points

• The dependent variable is the one that is expected to change in response to the manipulation of the independent variable, which in this case is the temperature.
• The time taken by the sugar to dissolve is directly affected by the temperature of the water.
• Therefore, it would be considered the dependent variable in this experiment, as it is the variable being measured and is expected to vary based on the changes in the independent variable (temperature).
• The quantity of sugar, the quantity of water, and temperature (as a controlled variable) would all remain constant during the experiment, making the time taken by sugar to dissolve the dependent variable that is being investigated.

Hence, it can be concluded that option 4 is the correct answer.

An open-ended question allows students to demonstrate their understanding of the concept while also showcasing their creativity, problem-solving skills, and ability to make logical connections.

Key Points

• They may provide a range of insightful answers, discussing potential challenges, adaptations, or differences in human perception without binocular vision.
• "What would have happened if human eyes did not have binocular vision?" This question prompts students to engage in critical thinking and reflection as they consider the potential consequences of the absence of binocular vision.
• In responding to this question, students are encouraged to analyze the importance and benefits of binocular vision, such as depth perception, the ability to perceive distance accurately, and the merging of visual inputs from both eyes.
• They need to think about how the absence of binocular vision may impact human activities, spatial awareness, and the perception of three-dimensional objects in their surroundings.

Hence, it can be concluded that option 4 is the correct answer.

The teacher is using an analogy by comparing the structure of an atom to the solar system, which the students are already familiar with.

Key Points

• By drawing a parallel between the massive nucleus and the sun, as well as the electrons and the planets, the teacher is creating a relatable image for the students.
• This analogy helps the students visualize and understand the abstract concept of the atomic structure by relating it to something more familiar and concrete.
• Analogies are a powerful teaching tool as they allow students to connect new information with existing knowledge, aiding in comprehension and retention.
• By using analogies, teachers can make complex concepts more accessible and facilitate understanding by providing a point of reference.
• In this case, the analogy of the solar system helps students grasp the basic arrangement of particles within an atom and fosters a deeper understanding of its structure.

Hence, it can be concluded that option 4 is the correct answer.

"Reports actual experimental data despite the unexpected results" is the most suitable indicator for assessing science students on their value of honesty.

Key Points

• This option emphasizes the student's integrity in accurately documenting and presenting experimental data, even if the outcomes deviate from their expectations.
• It showcases their willingness to embrace the truth and not manipulate or conceal information to fit preconceived notions.
• By reporting unexpected results, students demonstrate their commitment to scientific integrity, transparency, and the pursuit of knowledge.
• This indicator highlights their honesty in acknowledging and sharing data that may challenge existing theories or hypotheses, fostering a culture of intellectual honesty and advancement in the scientific community.

Hence, it can be concluded that option 2 is the correct answer.

Option 2 suggests that the historical validity of science curriculum is not helpful in appreciating that science is unaffected by social factors.

Key Points

• However, this argument overlooks the undeniable influence of social factors on scientific knowledge. Science is a human endeavor shaped by cultural, economic, and political contexts.
• Ignoring the impact of social factors limits students' understanding of the complex relationship between science and society.
• Recognizing this influence allows students to critically examine scientific theories, biases, and applications, promoting a more nuanced understanding of scientific knowledge.
• By studying the historical validity of science curriculum, students gain insight into how societal norms and beliefs have shaped scientific progress.
• This understanding encourages students to engage in discussions about the social and ethical implications of scientific advancements, fostering a more comprehensive scientific literacy.

Hence, it can be concluded that option 2 is the correct answer.

Scientific terms often have specific meanings within the context of science that may differ from their everyday usage.

Key Points

• It is important for science teachers to clarify and explain these specialized meanings to students.
• By highlighting the unique definitions and uses of scientific terms, teachers can promote accuracy and precision in scientific communication.
• Failing to emphasize this distinction may lead to misconceptions and misunderstandings among students, hindering their ability to comprehend scientific concepts effectively.

Hence, it can be concluded that option 2 is the correct answer.