General Science — MCQ Practice Questions & Answers

Question 1

Which quantum number determines the shape of an orbital?

Accepted Answer

Correct answer: B. Azimuthal quantum number (l) — The azimuthal quantum number (l) determines the shape of the orbital (s, p, d, f)

Answer

A. Principal quantum number (n)

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C. Magnetic quantum number (m)

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D. Spin quantum number (s)

Question 2

A wire of resistance R is stretched to double its length. What is the new resistance?

Accepted Answer

Correct answer: C. 4R — Resistance R = ρL/A. When length doubles, L becomes 2L and area becomes A/2 (volume constant). New R = ρ(2L)/(A/2) = 4ρL/A = 4R

Answer

A. R

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B. 2R

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D. R/2

Question 3

Which phenomenon causes the sky to appear blue during daytime?

Accepted Answer

Correct answer: C. Rayleigh scattering — Blue light has shorter wavelength and is scattered more by atmospheric molecules (Rayleigh scattering)

Answer

A. Reflection of light

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B. Refraction of light

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D. Total internal reflection

Question 4

A charged particle moves in a magnetic field. Under what condition does it move in a straight line?

Accepted Answer

Correct answer: A. Velocity is parallel to magnetic field — Lorentz force F = q(v × B). When v is parallel to B, the cross product is zero, so no force acts

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B. Velocity is perpendicular to magnetic field

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C. Magnetic field is very strong

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D. Particle has positive charge

Question 5

A projectile is launched at an angle of 45° with initial velocity 20 m/s. What is the maximum height reached? (g = 10 m/s²)

Accepted Answer

Correct answer: B. 10 m — Vertical component of velocity: u_y = 20 sin(45°) = 20/√2 = 10√2 m/s. Maximum height h = u_y²/(2g) = (10√2)²/(2×10) = 200/20 = 10 m.

Answer

A. 5 m

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C. 15 m

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D. 20 m

Question 6

The first law of thermodynamics relates to which principle?

Accepted Answer

Correct answer: A. Conservation of energy — The first law of thermodynamics (ΔU = Q - W) states that energy cannot be created or destroyed, only transferred. It is based on conservation of energy.

Answer

B. Conservation of momentum

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C. Conservation of angular momentum

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D. Conservation of charge

Question 7

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

Accepted Answer

Correct answer: B. 44 V — # Transformer Voltage Calculation A transformer changes voltage based on the ratio of turns in its primary and secondary coils. **Step 1: Identify the Transformer Equation** For an ideal transformer, the voltage ratio equals the turns ratio between the primary and secondary coils. \frac{V_{	ext{primary}}}{V_{	ext{secondary}}} = \frac{N_{	ext{primary}}}{N_{	ext{secondary}}} **Step 2: Substitute Given Values and Solve** We have: N_{	ext{primary}} = 500 turns, N_{	ext{secondary}} = 100 turns, and V_{	ext{primary}} = 220	ext{ V} \frac{220}{V_{	ext{secondary}}} = \frac{500}{100} V_{	ext{secondary}} = 220 	imes \frac{100}{500} = 220 	imes \frac{1}{5} = 44	ext{ V} **The secondary voltage is 44 V.** **Answer: (B) 44 V**

Answer

A. 22 V

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C. 110 V

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D. 220 V

Question 8

Which of the following pairs correctly represents the SI units of momentum and impulse respectively?

Accepted Answer

Correct answer: C. kg·m/s and N·s — # SI Units of Momentum and Impulse Momentum and impulse are related concepts in physics, but they represent different physical quantities with distinct SI units. Step 1: **Determine the SI Unit of Momentum** Momentum is defined as the product of mass and velocity. Using the fundamental SI units of mass (kg) and velocity (m/s), we can derive momentum's unit: 	ext{Momentum} = m 	imes v = 	ext{kg} 	imes \frac{	ext{m}}{	ext{s}} = 	ext{kg·m/s} Step 2: **Determine the SI Unit of Impulse** Impulse is defined as the product of force and time, or equivalently, the change in momentum. Using the SI unit of force (Newton = N = kg·m/s²) and time (seconds = s): 	ext{Impulse} = F 	imes t = 	ext{N} 	imes 	ext{s} = 	ext{kg·m/s}^2 	imes 	ext{s} = 	ext{N·s} Alternatively, since impulse equals change in momentum: 	ext{Impulse} = \Delta p = 	ext{kg·m/s (same as momentum)} Both perspectives confirm that impulse is measured in N·s, which is equivalent to kg·m/s. **The correct answer is (C): kg·m/s and N·s — momentum is measured in kg·m/s and impulse is

Answer

A. kg·m/s

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B. N/s and kg·m/s²

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D. kg·m/s² and N·s

General Science - MCQ Practice Questions