General Science — MCQ Practice Questions & Answers

Question 1

The escape velocity from the surface of a planet depends on which two fundamental properties of that planet?

Accepted Answer

Correct answer: B. Mass and radius — Escape velocity is mathematically derived as v = √(2GM/R), where G is gravitational constant, M is the planet's mass, and R is its radius. These two properties directly determine the gravitational field strength at the planet's surface, which defines the minimum velocity needed to escape gravitational attraction.

Answer

A. Radius and temperature

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C. Density and temperature

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D. Atmospheric pressure and mass

Question 2

Speed of sound in air?

Accepted Answer

Correct answer: B. 343 m/s — ~343 m/s at 20°C.

Answer

A. 300 m/s

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C. 400 m/s

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D. 250 m/s

Question 3

A lens has a focal length of 15 cm. What is its power?

Accepted Answer

Correct answer: A. +6.67 D — Power P = 1/f (in meters). P = 1/0.15 = 6.67 Diopters (positive for converging lens)

Answer

B. -6.67 D

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C. +2.25 D

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D. -2.25 D

Question 4

An object is placed 30 cm in front of a concave mirror with focal length 10 cm. Where is the image formed?

Accepted Answer

Correct answer: B. 15 cm in front of the mirror — **The mirror equation relates object distance, image distance, and focal length to locate where an image forms in a concave mirror.** Step 1: [Identify Given Values] For this concave mirror problem, we extract the known measurements from the question. 	ext{Object distance } (u) = 30 	ext{ cm} 	ext{Focal length } (f) = 10 	ext{ cm} 	ext{Image distance } (v) = ? Step 2: [Apply Mirror Equation] The mirror equation relates these three quantities and allows us to solve for the unknown image distance. \frac{1}{f} = \frac{1}{u} + \frac{1}{v} Substituting the values: \frac{1}{10} = \frac{1}{30} + \frac{1}{v} \frac{1}{v} = \frac{1}{10} - \frac{1}{30} \frac{1}{v} = \frac{3}{30} - \frac{1}{30} = \frac{2}{30} = \frac{1}{15} v = 15 	ext{ cm} Since v is positive, the image forms in front of the mirror (on the same side as the object). **The image is formed 15 cm in front of the mirror. Answer: (B)**

Answer

A. 15 cm behind the mirror

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C. 20 cm in front of the mirror

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D. 20 cm behind the mirror

Question 5

A transformer has 500 turns in primary and 100 turns in secondary coil. If primary voltage is 220V, what is the secondary voltage?

Accepted Answer

Correct answer: A. 44 V — Using transformer equation Vs/Vp = Ns/Np, we get Vs = 220 × (100/500) = 44 V

Answer

B. 1100 V

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C. 22 V

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D. 110 V

Question 6

A current-carrying conductor is placed in a magnetic field perpendicular to it. What force acts on it?

Accepted Answer

Correct answer: B. Lorentz force — The force on a current-carrying conductor in a magnetic field is called the Lorentz force, given by F = BIL

Answer

A. Gravitational force

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C. Electrostatic force

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D. Frictional force

Question 7

A radioactive element has a half-life of 10 years. After 30 years, what fraction of the original sample remains?

Accepted Answer

Correct answer: C. 1/8 — After 3 half-lives (30 years), the fraction remaining = (1/2)³ = 1/8

Answer

A. 1/2

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B. 1/4

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D. 1/16

Question 8

Which statement about elastic collisions is correct?

Accepted Answer

Correct answer: B. Kinetic energy is conserved — In elastic collisions, both momentum and kinetic energy are conserved

Answer

A. Momentum is not conserved

Answer

C. Objects always stick together

Answer

D. Maximum energy is lost

General Science - MCQ Practice Questions