Free Physics in Daily Life MCQs with Answers

241. Which of the following science is considered "mother of all sciences"?

• A. Biology
• B. Mathematics
• C. Physics
• D. Chemistry

Explanation: Mathematics is often called the mother of all sciences because it provides the language and quantitative tools used to express scientific laws. This is a conventional description rather than a strict scientific classification.

242. speed of sound in dry air at 20 °C is___________?

• A. 353 m/s
• B. 345 m/s
• C. 343 m/s
• D. none of them

Explanation: At 20 °C, sound travels through dry air at approximately 343 metres per second. The speed changes with temperature, which is why values such as 331 m/s apply to colder air.

243. Sound travels about ___________times faster in water than in air.

• A. 2
• B. 3
• C. 4
• D. 5

Explanation: Sound travels at about 1,480 m/s in water compared with about 343 m/s in air, giving a ratio a little over four. Thus, the nearest whole-number estimate is four times faster.

244. Dental mirror is what type of a mirror?

• A. Convex mirror
• B. Concave mirror
• C. Plane mirror
• D. none of these

Explanation: A concave mirror gives a dentist a magnified, upright image of a nearby tooth when the tooth is within the focal length. A convex mirror would produce a smaller image.

245. Which one of the following is not vector quantity _______?

• A. Acceleration
• B. Displacement
• C. Speed
• D. Force

Explanation: Speed has magnitude only, so it is a scalar quantity. Acceleration, displacement and force each require both magnitude and direction and are vectors.

246. A temporary magnet should be made from _______?

• A. Copper
• B. Tin
• C. Iron
• D. None

Explanation: Soft iron is suitable for a temporary magnet because it becomes magnetised easily and loses magnetism when the magnetising field is removed. Copper and tin do not have this useful magnetic behaviour.

247. The unit of torque in International system of unit is _________?

• A. Newton
• B. Newton-Meter
• C. Kilogram
• D. Meter

Explanation: Torque equals force multiplied by perpendicular distance from the axis, so its SI unit is newton-metre (N m). Newton alone measures force, not turning effect.

248. According to quantum theory of light, photons are _______?

• A. Waves
• B. Particles
• C. Energy packets
• D. Electromagnetic

Explanation: Quantum theory treats a photon as a discrete packet, or quantum, of electromagnetic energy. Photons also show wave-particle duality, but “energy packets” is the most precise option here.

249. How many mm are there in 10 cm?

• A. 100mm
• B. 200mm
• C. 50mm
• D. 10mm

Explanation: One centimetre equals 10 millimetres, so 10 cm equals 10 × 10 = 100 mm.

250. Which of the following is the SI unit of volume?

• A. Meter cube
• B. Cm cube
• C. mm cube
• D. Km cube

Explanation: The SI base unit of length is the metre, so the derived SI unit of volume is the cubic metre, written m³. Cubic centimetres and cubic kilometres are volume units but are not the standard SI unit.