Free Physics in Daily Life MCQs with Answers

171. Freezing point of water at Fahrenheit Scale is?

• A. 0 °F
• B. 212 °F
• C. 32 °F
• D. -32 °F

Explanation: Water freezes at 32 °F, which corresponds to 0 °C. The 212 °F value is its boiling point at standard atmospheric pressure.

172. Velocity of sound in air does not change with the change of?

• A. Temperature of air
• B. Pressure of air
• C. Moisture content in air
• D. Wind in the direction of propagation of sound

Explanation: At a fixed temperature, sound speed in an ideal gas is essentially independent of air pressure because both density and pressure change proportionally. Temperature, humidity and wind can affect the speed measured relative to the ground or the medium.

173. The weakest of all fundamental forces is the ________________?

• A. Gravitational force
• B. Electrostatic force
• C. Magnetic force
• D. Nuclear force

Explanation: Gravity is the weakest fundamental interaction, although it dominates astronomical structures because masses are always attractive and cannot cancel. The strong nuclear force is the strongest, while electromagnetic force is much stronger than gravity.

174. An egg sinks in soft water but floats in a concentrated solution of salt because?

• A. egg absorbs salt from the solution and expands
• B. albumin dissolves in salt solution and egg becomes lighter
• C. the density of salt solution exceeds the density of eggs
• D. water has high surface tension

Explanation: An object floats when the liquid's density is greater than the object's average density. Concentrated salt solution is denser than the egg, whereas fresh water is slightly less dense, so the egg sinks in fresh water.

175. The type of mirrors used in the headlamp of cars is ____________?

• A. Parabolic concave
• B. Plane
• C. Spherical convex
• D. Cylindrical concave

Explanation: A parabolic concave reflector places the bulb near its focus and produces a nearly parallel beam of light. Plane and convex mirrors cannot focus the bulb's rays into the forward beam required in a headlamp.

176. SI unit of Illumination is ________?

• A. Candela
• B. Flux
• C. Lux
• D. None of these

Explanation: Lux is the SI unit of illumination, measuring luminous flux received per unit area. Candela measures luminous intensity, not illumination.

177. Which gas is commonly used in balloons and airships?

• A. Helium
• B. Hydrogen
• C. Carbon
• D. Chlorine

Explanation: Helium is commonly used because it is lighter than air and non-flammable. Hydrogen also provides lift but is highly flammable, making it less suitable for ordinary balloons and airships.

178. How many pounds in a kg?

• A. 2.20
• B. 2.30
• C. 2.40
• D. 2.50

Explanation: One kilogram equals approximately 2.2046 avoirdupois pounds, normally rounded to 2.20 pounds. The larger choices are progressively less accurate approximations.

179. How many grams in a pound?

• A. 451
• B. 453
• C. 455
• D. 457Standardized & Admissions Tests

Explanation: One avoirdupois pound contains 453.592 grams, which rounds to 454 grams or is commonly stated in approximate MCQs as 453 grams. Thus 453 is the closest listed choice.

180. How many ounces in a pound?

• A. 10
• B. 12
• C. 14
• D. 16

Explanation: The avoirdupois pound used for ordinary weight contains 16 ounces. This is a fixed conversion, unlike the separate troy system used for precious metals.