CBSE Class 10 Science Questions with Answers

CBSE Class 10 Science Questions With Answers are one of the important resources for students preparing for their upcoming board examination. Especially when it comes to science then a clear understanding of Physics, Chemistry, and Biology is very crucial. The major clarity of concepts is driven by practicing the Class 10 Science important questions

For those focusing on specific subjects, CBSE Class 10 Physics Questions cover topics such as motion, force, and energy, while CBSE Class 10 Chemistry Questions explain chemical reactions, compounds, and everyday applications of chemistry. CBSE Class 10 Biology Questions focus on life processes, organisms, and the environment, aiding students in retaining essential knowledge effectively.

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CBSE Class 10 Science Questions With Answers 

1. On the Earth, the Sun rises in the east and sets in the west. Will it be the same on Venus?

Answer: No.

Hint: This concept is related to the rotation of planets. The apparent motion of the Sun depends on the planet’s rotation, not the Sun’s own motion.

Complete step-by-step answer:
The Sun rises in the east and sets in the west on Earth because the Earth rotates from west to east. Considering only Earth’s rotation about its axis, the motion of the Sun appears from east to west. The apparent movement is due to Earth’s spin, not the Sun’s motion. Venus, however, has a retrograde rotation; it spins clockwise from east to west, opposite to Earth’s rotation. Consequently, standing on Venus, the Sun would rise in the west and set in the east. Venus and Uranus are unique in the solar system for this clockwise rotation.

Note: Focusing on planetary rotation simplifies understanding apparent sunrise and sunset directions. Retrograde rotation is uncommon and explains differences in sunrise directions on other planets.

2. The speed of light is _____ km/s.

Answer: The speed of light is 300,000 km/s.

Hint: The speed of light, denoted by ccc, is a universal constant.

Complete step-by-step answer:
The speed of light in vacuum is exactly 299,792,458 meters per second. Converting this to kilometers per second:

The speed of light is constant in all inertial frames and represents the ultimate speed limit. At speeds near ccc, relativistic mechanics apply, affecting mass, time, and energy. Subatomic particles can approach, but never exceed, this speed.

Note: This constancy is a cornerstone of Einstein’s special relativity and underpins technologies like GPS, astronomy, and particle physics.

3. What is a moment? Give an example.

Answer: Moment, or torque, is the tendency of a force to rotate a body about a pivot.

Formula Used:

Complete step-by-step answer:
A moment causes rotation instead of linear motion. Clockwise rotation is considered positive, and anticlockwise rotation negative. The principle of moments states that if a system is in equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments.

For example, a door hinged on one side acts as a pivot. Two people push from opposite sides with equal force. No rotation occurs due to equilibrium. If one stops pushing, the door rotates about the hinges. The turning effect increases if the force is applied farther from the hinges, explaining why doorknobs are opposite hinges.

Note: Moments also apply to other quantities, such as angular momentum (first moment of momentum) or moment of inertia (second moment of mass). They represent rotational analogues of linear quantities.

4. Refractive index of glass is 1.5. What does it mean?

Answer: Light travels 1.5 times slower in glass than in a vacuum.

Hint: Refractive index measures how much light slows down in a medium.

Complete step-by-step answer:

Refractive index also varies with wavelength; violet light bends more than red light in glass.

Note: Refractive index is dimensionless. Some metals, like gold and silver, have refractive indices less than 1 under certain conditions. This concept is critical in designing lenses, optical fibres, and prisms.

5. What is displacement?

Answer: Displacement is the shortest straight-line distance from an object’s initial position to its final position, with a specified direction.

Hint: Displacement is a vector quantity with both magnitude and direction.

Complete step-by-step answer:
Displacement is defined as:

It differs from distance traveled, which measures the actual path length without direction. Displacement is always along a straight line connecting the initial and final points. In one-dimensional motion, the direction can be indicated with a positive or negative sign.

Note: Distance is scalar, while displacement is vectorial. Velocity is defined as the rate of change of displacement. Understanding the difference is crucial in physics for analyzing motion accurately.

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6. Bleaching powder is made up of:

A. Lime and chlorine
B. Soda ash and chlorine
C. Chlorine and charcoal
D. None of these

Answer: A. Lime and chlorine

Hint: Bleaching powder is a commercial inorganic product, chemically called calcium hypochlorite,

 

Complete step-by-step answer:
Bleaching powder is a yellowish-white powder with a chlorine smell. It is produced by passing chlorine gas over dry slaked lime

It acts as a disinfectant, bleach for laundry, and oxidizer in industry.

Note: Free lime in bleaching powder prevents a clear solution. A good sample contains around 30–35% available chlorine.

7. What is the full form of PNG?

A. Petrol Natural Gas
B. Piped Natural Gas
C. Pressurised Natural Gas
D. Pure Natural Gas

Answer: B. Piped Natural Gas

Hint: PNG is domestic gas supplied through pipelines for cooking purposes.

Complete step-by-step answer:
PNG is delivered via a closed pipeline network, and consumers pay according to usage. It is safe, economical, and pollution-free. Unlike CNG (compressed natural gas), PNG remains in gaseous form at low pressure.

Note: Do not confuse “piped” with “pressurized” or “pure.” Pressurized natural gas is CNG, while PNG is simply supplied through pipelines.

8. What are the various types of Silk?

Answer: Natural silk types include Muga silk, Mulberry silk, Tasar silk, and Eri silk.

Hint: Silk is obtained from silkworms, processed into threads, and woven into fabric.

Complete step-by-step answer:
Muga silk is the costliest, historically reserved for royalty. Mulberry silk is most commonly used globally, sourced from Bombyx mori. Tasar silk is coarse, coppery-colored, and used for furniture. Eri silk, also called Peace silk, is harvested without killing silkworms, making it strong yet soft.

Note: Spider silk is considered a type of Muga silk. Silk grades A, B, and C denote quality, with grade A being the finest. Chiffon fabric may combine silk with other materials.

9. The sulphur molecule can be represented as:

a. Cubical structure
b. Spherical structure
c. Tetrahedral structure
d. W-shaped ring structure

Answer: d. W-shaped ring structure

Hint: Sulphur forms cyclic molecules with eight atoms to complete the octet.

Complete step-by-step answer:
Sulphur has six valence electrons and forms a ring with eight atoms, each sharing two electrons with neighbouring atoms. The puckered crown (W-shaped) structure allows each atom to satisfy the octet rule.

Note: Sulphur is abundant, non-metallic, multivalent, and forms multiple allotropes. It is essential in sulfuric acid manufacture, fertilizers, batteries, and chemical processing.

10. What is Ag in Chemistry?

Answer: Silver

Hint: Ag is the chemical symbol derived from Latin “argentum.”

Complete step-by-step answer:
Silver is a transition metal with atomic number 47. It has excellent electrical and thermal conductivity, high reflectivity, and malleability. It is widely used in jewelry, coins, mirrors, and electrical components. In biology and medicine, silver exhibits antimicrobial properties and is used in wound dressings and coatings for medical devices.

Note: Ag is stable in pure water and air but tarnishes in the presence of sulfur.

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11. What is the chemical formula of chalk?

Answer:

Hint: Chalk is primarily calcium carbonate, a sedimentary rock.

Complete step-by-step answer:
Chalk consists of calcite mineral, mostly white, and forms from the skeletal remains of marine organisms. Its formula is a soft and porous substance. Chalk reacts with acids, releasing carbon dioxide. Modern blackboard chalk may contain gypsum for consistency.

Note: Chalk is used for writing, lime production, and in cement. Natural chalk is highly porous, capable of storing and slowly releasing water.

12. What is the difference between distance and displacement?

Answer: Distance is the total path covered by an object regardless of direction, whereas displacement is the shortest straight-line distance between the initial and final positions of an object, including direction.

Hint: Distance is scalar, while displacement is vectorial.

Complete step-by-step answer:
Distance measures the actual path traveled and is always positive, with no directional information. Displacement measures the change in position and is calculated as:

Displacement can be zero even if the object has travelled a large distance, for example, when returning to the starting point. Distance is additive along the path, while displacement depends only on the initial and final positions.

Note: Understanding the distinction is fundamental in physics, especially when calculating velocity and acceleration. Displacement is used in vector equations, while distance is relevant for total movement analysis.

13. What is the difference between mass and weight?

Answer: Mass is the amount of matter in a body and is constant, while weight is the force exerted on the body due to gravity and can vary with location.

Hint: Weight depends on the acceleration due to gravity, whereas mass does not.

Complete step-by-step answer:
Weight is calculated using the formula:

where mmm is mass and ggg is acceleration due to gravity. Mass is measured in kilograms (kg) and is intrinsic to the body. Weight is measured in newtons (N) and varies with planetary gravity. For example, a 50 kg object weighs 490 N on Earth but only 185 N on the Moon.

Note: Mass is a scalar quantity, while weight is a vector, acting toward the center of the planet. Distinguishing mass and weight is essential in mechanics and engineering.

14. What is Ohm’s law?

Answer: Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant.

Formula Used:

where VVV is voltage, III is current, and RRR is resistance.

Complete step-by-step answer:
Ohm’s law implies that doubling the voltage doubles the current for a fixed resistance. It is fundamental in electrical circuit analysis and helps in calculating voltage, current, and resistance in circuits.

Note: Ohm’s law applies only to ohmic conductors, where resistance remains constant with changing voltage and current. Non-ohmic devices like diodes and transistors do not follow this law.

15. What is the chemical formula of water?

Answer:

Hint: Water consists of two hydrogen atoms bonded to one oxygen atom.

Complete step-by-step answer:
Water molecules form covalent bonds between hydrogen and oxygen. The oxygen atom shares one electron with each hydrogen atom, resulting in a bent molecular shape with an angle of approximately 104.5°. Water is a polar molecule, leading to hydrogen bonding, high surface tension, and excellent solvent properties.

Note: Water is essential for life, used in agriculture, industry, and domestic activities. Its molecular properties explain phenomena like ice floating, capillary action, and high heat capacity.

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16. What is the chemical formula of common salt?

Answer:

Hint: Common salt is chemically called sodium chloride.

Complete step-by-step answer:
Sodium chloride consists of sodium cations and chloride anions in a 1:1 ratio. It forms a crystalline lattice, giving it a high melting point and solubility in water. Salt is vital for human nutrition and used in food preservation.

Note: NaCl is also used industrially in the production of chlorine, sodium hydroxide, and in de-icing roads.

17. What is the difference between speed and velocity?

Answer: Speed is the rate of motion irrespective of direction (scalar), whereas velocity is the rate of motion with a specified direction (vector).

Hint: Velocity can be negative or positive depending on direction, but speed is always positive.

Complete step-by-step answer:
Speed is calculated as:

Speed=DistanceTime\text{Speed} = \frac{\text{Distance}}{\text{Time}}Speed=TimeDistance​

Two objects can have the same speed but different velocities if they move in different directions.

Note: Velocity is crucial in vector analysis, while speed is used for general motion description.

18. What is the difference between scalar and vector quantities?

Answer: Scalars have only magnitude, while vectors have both magnitude and direction.

Hint: Scalars include temperature and mass; vectors include velocity and force.

Complete step-by-step answer:
Scalar quantities are added algebraically, while vector quantities require vector addition (using triangle or parallelogram rules). Magnitude alone describes a scalar, whereas vectors are represented by arrows indicating magnitude and direction.

Note: Correct understanding of scalar and vector quantities is essential in mechanics, electromagnetism, and other branches of physics.

19. What is the chemical formula of baking soda?

Answer:

Hint: Baking soda is also called sodium bicarbonate.

Complete step-by-step answer:
Sodium bicarbonate decomposes on heating to produce sodium carbonate, water, and carbon dioxide:

It is used in cooking, cleaning, and as an antacid.

Note: Baking soda’s alkaline nature allows it to neutralize acids, making it useful in both food preparation and medicine.

20. What is the chemical formula of washing soda?

Answer:

Hint: Washing soda is also called sodium carbonate decahydrate.

Complete step-by-step answer:
Washing soda is a crystalline compound containing ten water molecules. It is used in cleaning, water softening, and in glass manufacturing. It reacts with acids to release carbon dioxide.

Note: Washing soda is different from baking soda in composition, alkalinity, and industrial uses.

Read More: CBSE Class 10 Maths Questions with Answers

CBSE Class 10 Science Questions With Answers FAQs

1. What are some important questions for Class 10 Science?

Important questions for Class 10 Science encompass key topics across Physics, Chemistry, and Biology. These include concepts like Newton's Laws of Motion, chemical reactions, and the structure of the human eye. Focusing on these areas can aid in comprehensive exam preparation.

2. How can I prepare for CBSE Class 10 Science exams?

Effective preparation for CBSE Class 10 Science involves understanding the NCERT syllabus, practicing previous year question papers, and focusing on important topics. Utilizing study materials from reputable sources can enhance conceptual clarity and exam readiness.

3. What are the most repeated questions in CBSE Class 10 Science?

The most repeated questions in CBSE Class 10 Science often cover topics like chemical reactions, laws of motion, and the human digestive system. Reviewing these frequently asked questions can help students anticipate exam patterns and focus their studies accordingly.

4. How can I access CBSE Class 10 Science sample papers?

CBSE Class 10 Science sample papers can be accessed through official CBSE websites and educational platforms like SelfStudys. These sample papers simulate the actual exam format, providing students with practice opportunities to improve their performance.