MCQs — 5 each from the topics: Motion, Light, Sound, Electricity, Force, and Energy, each with clear explanatory answers.

🔵 MOTION — 5 MCQs

1. Uniform motion means:

A. Speed keeps changing
B. Speed remains constant
C. Object changes direction repeatedly
D. Motion in a circle

Answer: B. Speed remains constant
✔ In uniform motion, equal distances are covered in equal intervals of time.

2. The slope of a distance–time graph gives:

A. Acceleration
B. Speed
C. Force
D. Momentum

Answer: B. Speed
✔ A steeper slope means higher speed.

3. A car moves 60 km in 2 hours. Its speed is:

A. 20 km/h
B. 30 km/h
C. 40 km/h
D. 50 km/h

Answer: B. 30 km/h
✔ Speed = distance / time = 60/2 = 30 km/h.

4. A body is in rest when:

A. It moves slowly
B. It moves fast
C. It changes its position
D. It does NOT change its position

Answer: D. Does NOT change its position
✔ If position does not change with time, it is at rest.

5. The SI unit of speed is:

A. m/s
B. km/h
C. cm/s
D. m/min

Answer: A. m/s
✔ m/s is the SI standard, though km/h is used daily.

🔵 LIGHT — 5 MCQs

6. Light travels fastest in:

A. Water
B. Glass
C. Air
D. Vacuum

Answer: D. Vacuum
✔ No particles → maximum speed (3×10⁸ m/s).

7. The mirror used in shaving mirrors is:

A. Plane
B. Convex
C. Concave
D. Cylindrical

Answer: C. Concave
✔ It magnifies the face when held close.

8. The splitting of white light into colours is called:

A. Reflection
B. Refraction
C. Dispersion
D. Absorption

Answer: C. Dispersion
✔ It forms spectra like in a prism or rainbow.

9. Which colour has the longest wavelength?

A. Violet
B. Blue
C. Green
D. Red

Answer: D. Red
✔ Red bends the least; violet bends the most.

10. A periscope works due to:

A. Refraction
B. Diffraction
C. Total internal reflection
D. Reflection from plane mirrors

Answer: D. Reflection from plane mirrors
✔ Two mirrors at 45° reflect light twice.

🔵 SOUND — 5 MCQs

11. Sound is produced due to:

A. Flow of current
B. Vibrations
C. Reflection of light
D. Heat

Answer: B. Vibrations
✔ All sound originates from vibrating objects.

12. The SI unit of frequency is:

A. Hertz
B. Watt
C. Joule
D. Newton

Answer: A. Hertz
✔ 1 Hz = 1 vibration per second.

13. Sound travels fastest in:

A. Air
B. Water
C. Steel
D. Vacuum

Answer: C. Steel
✔ Solids > liquids > gases because particles are closest in solids.

14. Echoes occur when the reflecting surface is at least:

A. 1 m away
B. 5 m away
C. 17 m away
D. 50 m away

Answer: C. 17 m
✔ Time for sound to return must be ≥ 0.1 s.

15. Ultrasonic waves have frequency:

A. Below 20 Hz
B. 20–20,000 Hz
C. Above 20,000 Hz
D. Above 100 Hz only

Answer: C. Above 20,000 Hz
✔ Humans cannot hear ultrasound; dolphins and bats can.

🔵 ELECTRICITY — 5 MCQs

16. What flows in an electric circuit?

A. Protons
B. Neutrons
C. Electrons
D. Atoms

Answer: C. Electrons
✔ Current is the flow of electrons from –ve to +ve terminal.

17. A device that opens or closes a circuit is:

A. Fuse
B. Battery
C. Switch
D. Bulb

Answer: C. Switch
✔ A closed switch allows current, an open switch stops it.

18. The SI unit of resistance is:

A. Volt
B. Ampere
C. Coulomb
D. Ohm

Answer: D. Ohm
✔ Resistance opposes the flow of current.

19. Which conductor has the least resistance?

A. Silver
B. Copper
C. Aluminium
D. Iron

Answer: A. Silver
✔ Best conductor → lowest resistance.

20. A fuse works on the principle of:

A. Reflection
B. Magnetic effect
C. Overheating of thin wire
D. Chemical reaction

Answer: C. Overheating of thin wire
✔ When current exceeds limit → wire melts → circuit breaks → prevents fire.

🔵 FORCE — 5 MCQs

21. Force can:

A. Only stop motion
B. Only start motion
C. Only change shape
D. Do all of the above

Answer: D. All
✔ Force can start, stop, speed up, slow down, change direction, or change shape.

22. A person standing on Earth experiences:

A. Only gravity
B. Only normal reaction
C. Both gravity and normal reaction
D. No force

Answer: C. Both
✔ Gravity pulls down → Earth pushes up → balanced forces.

23. Friction is a:

A. Contact force
B. Non-contact force
C. Balanced force
D. Nuclear force

Answer: A. Contact force
✔ It arises when two surfaces touch.

24. Which of these reduces friction?

A. Rough surfaces
B. Oil
C. Sand
D. More load

Answer: B. Oil
✔ Lubricants fill gaps → smoother motion → less friction.

25. The force that keeps a body moving in a circular path is:

A. Centrifugal force
B. Gravitational force
C. Centripetal force
D. Muscular force

Answer: C. Centripetal force
✔ Directed toward the center of the circle.

🔵 ENERGY — 5 MCQs

26. Energy stored in a stretched rubber band is:

A. Kinetic
B. Potential
C. Heat
D. Sound

Answer: B. Potential energy
✔ Due to its stretched position.

27. A moving car has:

A. Only potential energy
B. Only kinetic energy
C. Both kinetic and potential energy
D. No energy

Answer: C. Both
✔ Kinetic (motion) + potential (height, fuel’s chemical energy).

28. Which of these is NOT a renewable energy source?

A. Solar
B. Wind
C. Coal
D. Hydroelectric

Answer: C. Coal
✔ Fossil fuels are finite.

29. The energy of motion is called:

A. Heat energy
B. Kinetic energy
C. Chemical energy
D. Mechanical energy

Answer: B. Kinetic energy
✔ Faster motion → more kinetic energy.

30. In a hydroelectric power plant, the main energy conversion is:

A. Electrical → Mechanical
B. Solar → Electrical
C. Potential → Electrical
D. Sound → Electrical

Answer: C. Potential → Electrical
✔ Stored water at height → potential energy → kinetic → mechanical (turbine) → electrical.

SCIENCE MCQ FOR B.DES ENTRANCE EXAMS