Mathematics and Science PYQs

The Correct answer is Earth attracts the coin.

Explanation:

• The acceleration of a falling object near the surface of the Earth is due to the force of gravity, which is an attractive force exerted by the Earth on all objects. This acceleration is commonly denoted as "g" and is approximately 9.8 meters per second squared (m/s²).
• When a coin falls from the roof of a building toward the ground, it experiences the force of gravity pulling it downward. Initially, as the coin starts to fall, it has an initial velocity of zero. However, as time passes, the force of gravity causes the coin to accelerate. This means that the coin's velocity increases at a constant rate. In other words, with each passing second, the coin's speed increases by approximately 9.8 m/s.
• The coin is very light and doesn't directly influence its acceleration due to gravity. All objects, regardless of their mass, experience the same acceleration due to gravity if air resistance is negligible.
• The force of gravity is acting on the coin, which is why it accelerates. The presence of this force is what causes the coin to increase its speed continuously as it falls.
• While air resistance (air pushing the coin) does have an effect on falling objects, it is typically not the main factor when considering the increase in speed of a falling coin. In the absence of air resistance (in a vacuum), a coin would still accelerate due to the force of gravity.

Explanation:

The given information suggests that the bars AB and CD exhibit magnetic behavior.

(i) End A is repelled by end C: This implies that there is a like-pole repulsion between the ends A and C, which is a characteristic behavior of magnets.

(ii) Ends B and C are attracted towards each other: This also suggests magnetism because opposite poles attract.

(iii) Ends B and D repel each other: Similar to (i), this implies a like-pole repulsion, indicating magnetic behavior.

Based on these observations, it can be concluded that both AB and CD are magnets. Therefore, the correct option is:

Both AB and CD are magnets.

The Correct answer is 2KCl + Br2 → Cl2 + 2KBr

Explanation:

2Al + Cr₂O₃ → 2Cr + Al₂O₃

• This reaction is a redox reaction, where aluminum is oxidized to aluminum oxide (Al₂O₃) and chromium is reduced to chromium (Cr). Aluminum is more reactive than chromium, so it is able to oxidize chromium. This reaction is likely to occur.

Cu + 2H₂O → Cu(OH)₂ + H₂

• This reaction is a single displacement reaction, where copper is displaced from water by hydrogen. Hydrogen is more reactive than copper, so it is able to displace copper from water. This reaction is likely to occur.

Cl₂ + 2NaBr → Br₂ + 2NaCl

• This reaction is a double displacement reaction, where chlorine and bromine are exchanged. Both chlorine and bromine are halogens, and they have similar reactivity. This reaction is likely to occur.

2KCl + Br₂ → Cl₂ + 2KBr​

• This reaction is a displacement reaction, where potassium is displaced from potassium chloride by bromine. However, bromine is more reactive than potassium, so it is unlikely to be displaced by potassium. This reaction is least likely to occur.

The Correct answer is Paper does not reach ignition temperature.

Explanation:

• Paper will not catch fire unless it reaches its ignition temperature. The ignition temperature of paper is around 240 degrees Celsius. When a paper cup containing water is heated, the water absorbs the heat and prevents the paper from reaching its ignition temperature.
• The specific heat of paper is around 1.8 kJ/kg/K. This means that it takes a lot of energy to heat up paper. The water in the cup has a much higher specific heat of around 4.2 kJ/kg/K. This means that the water absorbs more heat than the paper, preventing the paper from reaching its ignition temperature.
• So, the reason why a paper cup containing water does not catch fire when heated with a candle placed below it is that the water absorbs the heat and prevents the paper from reaching its ignition temperature.

Additional Information

• Paper is non-combustible: Paper is combustible, meaning that it can catch fire. However, it will not catch fire unless it reaches its ignition temperature.
• Water has low specific heat: Water has a high specific heat, meaning that it takes a lot of energy to heat up water. This is why the water in the cup absorbs more heat than the paper, preventing the paper from reaching its ignition temperature.
• Paper has high specific heat: Paper has a low specific heat, meaning that it takes less energy to heat up paper than water. However, the water in the cup still absorbs more heat than the paper, preventing the paper from reaching its ignition temperature.

Concept:

Functional classification of joints

• The joints help us to rotate our shoulder, bend our knees and elbows, swivel our neck and more.
• By definition, a joint is a point where two bones meet to provide a framework that permits movement.
• Bones are attached to one another by tissues called ligaments. Muscles are attached to bones through tendons.

Functional classification of joints is based on the type and degree of movement permitted. There are six types of freely movable joint and are mentioned below with the examples.

Important Points

Ball and Socket Joints - 

• Here, one bone is hooked into the hollow space of another bone. This type of joint helps in rotatory movement.
• An example ball and socket joint are the shoulders.

Pivotal Joints - 

• In this type of joint, one bone has tapped into the other in such a way that full rotation is not possible.
• This joint aid in sideways and back-forth movement.
• An example of a pivotal joint in the neck.

Hinge Joints - 

• Hinge joints are like door hinges, where only back and forth movement is possible.
• Example of hinge joints is the ankle, elbows, and knee joints.

Saddle Joints - 

• Saddle joint is the biaxial joint that allows the movement on two planes–flexion/extension and abduction/adduction.
• For example, the thumb is the only bone in the human body having a saddle joint.

Condyloid Joints - 

• Condyloid joints are the joints with two axes which permit up-down and side-to-side motions.
• The condyloid joints can be found at the base of the index finger, carpals of the wrist, elbow and the wrist joints.
• This joint is also known as a condylar, or ellipsoid joint.

Gliding Joints - 

• Gliding joints are a common type of synovial joint.
• It is also known as a plane or planar joint.
• This joint permit two or more round or flat bones to move freely together without any rubbing or crushing of bones.
• This joint is mainly found in those regions where the two bones meet and glide on one another in any of the directions.
• The lower leg to the ankle joint and the forearm to wrist joint are the two main examples of gliding joints.

Hence correct answer is option 3.

The Correct answer is Both S1 and S2 are incorrect 

Explanation:

 

• S1: metallic oxides are always basic in nature.

This statement is incorrect. While many metallic oxides exhibit basic properties, there are exceptions. For example, some transition metal oxides can act as amphoteric, showing both acidic and basic properties.

• S2: Being electronegative in nature, metals readily react with oxygen.

This statement is incorrect. Metals typically react with oxygen to form metallic oxides, but this is not due to the electronegativity of metals. Metals generally lose electrons to form positive ions (cations) rather than gaining electrons, as electronegative non-metals do.

The Correct answer is Equal to its weight.

Explanation:

• The buoyant force acting on an object is equal to the weight of the fluid displaced by the object. In this case, the object is floating, so the buoyant force is equal to the weight of the object.
• The buoyant force is caused by the pressure difference between the top and bottom of the object. The pressure is greater at the bottom of the object because the fluid is denser at the bottom. This pressure difference creates a force that pushes the object upward.
• When the buoyant force is greater than the weight of the object, the object floats. If the buoyant force is less than the weight of the object, the object will sink. If the buoyant force is equal to the weight of the object, the object will rise to the surface of the liquid.

So, the buoyant force acting on an object that floats in a liquid with half of its volume submerged in the liquid is equal to its weight.

Important Points

• When the buoyant force of liquid is less than the weight of the object, the object will be submerged or sank.
• When the buoyant force of the liquid is greater than the weight of the object, the object will float on the surface of the liquid.
• NOTES: Buoyancy is the tendency of a liquid to exert an upward force on an object immersed in it.
• The buoyancy of a liquid depends upon the density of the fluid and the volume of the object immersed in the liquid.
• Thus we can say the buoyant force is greater if the volume of an object submerged in a liquid is Larger.

Key PointsHeart of a fish: 

• The heart of a fish consists of a relatively simple structure compared to other animals.
• It is a two-chambered organ, composed of an atrium and a ventricle.
• Deoxygenated blood enters the heart through the sinus venosus, a thin-walled chamber that acts as a collecting chamber for blood returning from the body.
• From there, the blood moves into the atrium, which contracts, pushing the blood into the ventricle.
• The ventricle is a muscular chamber responsible for pumping the blood throughout the fish's gills, where oxygen exchange occurs.
• After oxygenation, the blood returns to the heart, completing the circulation cycle.
• The heart's efficiency in fish is sufficient to meet their oxygen demands, considering their aquatic lifestyle and relatively lower metabolic rates compared to mammals and birds.
• Overall, the fish's heart structure is adapted to function effectively in its aquatic environment, ensuring a continuous flow of oxygenated blood to support its physiological needs.

Hence correct answer is option 4

The Correct answer is Speed is zero.

Explanation:

• A simple pendulum consists of a mass (bob) attached to a string or rod of a fixed length that swings back and forth under the influence of gravity. When the bob is released from the mean (equilibrium) position towards the extreme position (highest point on one side of the swing), its potential energy is at a maximum, and it begins to lose height while gaining kinetic energy.
• As the bob reaches the extreme position, it momentarily comes to a stop before reversing its motion and swinging back. At this point, its kinetic energy is converted into potential energy, and its speed becomes zero. This is because the bob reaches its highest point of the swing, and its velocity decreases to zero before it starts descending back towards the mean position.
• At the extreme position, the displacement is indeed maximum, as the bob is farthest from the mean position, but its speed is zero due to the reversal of direction. The acceleration is not maximum at the extreme position; it is actually zero as well because the bob is momentarily at rest before changing direction.

Therefore when the bob of a simple pendulum is released from the mean position towards the extreme position, its speed becomes zero.

Concept:

Vegetative propagation in plants

• Vegetative propagation in plants refers to the process of asexual reproduction, where new individuals are produced from the vegetative parts of the parent plant, such as stems, roots, or leaves, without involving the formation of seeds or spores.
• This method allows plants to reproduce rapidly and produce genetically identical offspring, also known as clones.

There are several methods of vegetative propagation:

1. From Roots: Vegetative propagation through roots take place in plants like sweet potato and dahlia, where tuberous roots are formed. The adventitious buds on these tuberous roots grow above the ground to form new plants.
2. Rhizomes and Runners: Some plants, like ginger and strawberries, produce specialized stems called rhizomes and runners, respectively, which can grow horizontally and produce new plants at nodes.
3. Tuber and Corms: These are modified underground stems that can give rise to new plants when separated and planted. The eye buds of potato tuber germinate into new plants.
4. Leaf Buds: In some plants like Bryophyllum, adventitious buds are formed at the leaf margins. Adventitious roots originate from these buds and give rise to new plants.

Therefore, we can say that vegetative propagation involves roots, stems and leaves.

Additional Information

• Vegetative propagation is beneficial for horticulture and agriculture as it allows for the quick and reliable multiplication of desirable plant traits.
• However, it can also lead to limited genetic diversity, making crops more susceptible to diseases and environmental changes.
• Therefore, a combination of sexual and vegetative propagation methods is often employed to maintain genetic variation and enhance plant resilience.

Some Artificial Methods - 

• Cuttings: This involves cutting a portion of the stem or branch from the parent plant and allowing it to develop roots and grow into a new plant. It's a common method for propagating many houseplants and ornamental plants.
• Grafting and Budding: These techniques involve joining a part of one plant with another plant (the rootstock or stock) to combine desirable traits. Grafting is commonly used for fruit trees and roses.
• Layering: In this method, a branch or stem of the parent plant is bent to the ground, covered with soil, and allowed to develop roots before being separated from the parent and becoming an independent plant.

Hence correct answer is option 3.

Pressure can be defined as continuous physical force exerted on or against an object by something in contact with it.

Key Points

• The activity that would be most suitable for illustrating the concept of pressure to students is Holding a strip of paper to the bottom lip and then blowing air from the mouth across the strip. Observing the direction in which the strip of paper moves.
• In this activity, the pressure of the air from the mouth pushes down on the strip of paper, while the atmospheric pressure pushes up on the other side of the strip.
• The difference in pressure causes the strip of paper to move upwards. This activity can be used to explain the concept of pressure in a simple and easy-to-understand way.
• Pushing an empty closed plastic bottle into a bucket of water and making observations can be used to illustrate the concept of buoyancy.

Hence, we can conclude that Holding a strip of paper to the bottom lip and then blowing air from the mouth across the strip is a suitable activity.

Process skills are the skills that are used to solve problems and complete tasks.

Key Points

• Breathe in and out normally. Find out how many times you breathe in and breathe out in a minute. This step involves measuring the breathing rate, so it requires the skill of Observation.
• Now count your breathing rate after a brisk walk, after running, and after complete rest. This is also a step that involves measurement.
• In which case, according to you, will the breathing rate be the fastest? This step asks the student to predict the outcome based on the measurements, so it involves prediction.

​Hence, we can conclude that the activity aims to develop Observation, prediction, and measurement among students.

Assessment refers to the systematic process of documenting and evaluating evidence to determine the knowledge, skills, attitudes, and performance of individuals.

Key Points

• Assessment in science should be comprehensive, meaning that it should assess students' knowledge, skills, and understanding of a wide range of scientific concepts and principles.
• Assessment in science should promote scientific inquiry, meaning that it should encourage students to ask questions, to design experiments, to collect data, and to draw conclusions.
• Assessment in science should facilitate the development of process skills, meaning that it should assess students' ability to use the scientific process.
• It should not be based on students' memorization of scientific principles and theories.

Hence, we can conclude that Assessment in science is based on students' memorization of scientific principles and theories is not aligned with the contemporary view of assessment in science.

Open-ended questions are questions that do not have a single correct answer. They require students to think critically and to use their knowledge to come up with a response.

Key PointsWhat would happen if we had no wood? is an open-ended question.

Here are some reasons why:

• It is not possible to find a single correct answer to this question. There are many things that would happen if we had no wood.
• The question requires students to think critically and to use their imagination.
• Students will need to consider the many different ways that wood is used in our lives, and they will need to hypothesize about what would happen if we did not have wood.
• The question does not have a predetermined answer. The response will vary depending on the student's knowledge and understanding of the topic.

Hence, we can conclude that "What would happen if we had no wood?" is an open-ended question.

The most effective teaching strategies, especially in science, often involve active student participation and discovery learning.

Key Points

• Writing the meaning of 'conduction' on the board and explaining it is a teacher-centered approach.
• Listing materials and asking students to categorize them introduces a hypothesis-testing approach. Students are engaged in making predictions based on their prior knowledge.
• Having students explore each material by placing it in the circuit is a discovery-based approach. Students directly interact with the materials without any preconceived notions.
• Demonstrating the activity and asking students to note down their observations is somewhat passive.

Hence, we can conclude that I will begin by having my students explore each material by placing it in the circuit. I would use their observations as the basis for categorizing materials as good or bad conductors of electricity.

Encouraging learners to ask questions is crucial in a science classroom, as it fosters curiosity and deeper understanding.

Key Points

• (A) Acknowledging learners’ questions as interesting, good, etc.: When learners' questions are acknowledged and appreciated, they feel valued and are more likely to ask questions in the future.
• (B) Providing opportunities for all learners to express themselves: Every student should have the chance to express their thoughts and concerns. If only a select few are given the opportunity, others may become hesitant to ask questions, fearing they might not get a chance to be heard.
• (C) Providing immediate answers to students' questions: While it might seem that immediate answers would encourage more questions, this can also discourage critical thinking.
• (D) Assessing learners on the quality of questions, not only answers: If students know that their questions will be valued and assessed, they might put more effort into crafting thoughtful, relevant queries.

Hence, we can conclude that statements (A), (B), and (D) can be used to encourage learners to ask questions in a science classroom.

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

Key Points

• Experiments are fundamental in many scientific disciplines, they aren't the only way scientific knowledge is generated.
• Observations, data collection, and theoretical work also play significant roles.
• Empirical evidence, which is information gathered from observations or experiments, is critical in science. It's used to validate or refute hypotheses, theories, or models.
• Scientific knowledge is built on accumulated evidence, but it's not always "sure" or absolute.
• Not all scientific conclusions undergo rigorous review, especially outside of formal publication in reputable journals.

Hence, we can conclude that Empirical evidence is used to support and refine ideas in science is true about science.

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

Key Points

• Harvey's discovery suggests there was empirical work done which aligns with (A) Science is based on empirical evidence.
• Harvey's views were initially ridiculed and later accepted suggesting the tentative nature of scientific discoveries, or (B) Science is tentative.
• The reactions and challenges Harvey faced, especially the societal aspect of him losing patients and being called a "circulator", underscores that (D) Science is socially and culturally embedded.

Hence, we can conclude that statements (B), (A) and (D) illustrate the nature of science.

An inference is a conclusion reached on the basis of evidence and reasoning. It's not a direct observation but rather a deduction made from observations.

Key Points

• Leaves of an aquatic plant are covered with waxy coating: This is a direct observation. If you looked at the leaves of an aquatic plant and noticed a waxy coating, you're simply stating what you saw.
• A climbing plant has thread-like spirally coiled structures arising from the stem: Again, this is an observation. It describes a specific physical characteristic of a climbing plant.
• Leaves of aquatic plants float and bend in water: This is another observation. If you placed aquatic plant leaves in water, you could directly see them floating and bending.
• Small-sized leaves of a desert plant help in reducing loss of water: This statement moves beyond simple observation.
• While you can directly observe that a desert plant has small leaves, the reason those leaves are small (to reduce water loss) isn't something you can see – it's something you conclude based on knowledge about desert conditions and plant adaptations.

Hence, we can conclude that Small sized leaves of a desert plant help in reducing the loss of water is an inference.

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

Key Points

• S1: Science is always beneficial for society. This is a broad and absolute statement.
• While science has undoubtedly brought about many beneficial advancements for society, it's also led to some technologies and applications with harmful consequences.
• Nuclear technology, for instance, has both beneficial uses (like power generation) and destructive applications (like nuclear weapons).
• Therefore, it's an overgeneralization to say science is "always" beneficial. This makes S1 potentially problematic or false.
• S2: The application of science has led to the invention of optical and electronic devices as well as computer and telecommunication technologies.
• This is a factual statement.
• The development of these technologies has been a direct result of scientific inquiry and application. This makes S2 true.

​Hence, we can conclude that S1 is false but S2 is true.