Physics: Units and Instruments MCQs – Page 2

Solved Everyday Science MCQs on SI units, measuring instruments, light, sound, heat and electricity, with short explanations for competitive exams.

1. 21

   At sea level, pure water boils at:

   A90 °CB100 °CC110 °CD120 °C

   Correct answer: B. 100 °C

   Water boils at 100 °C (212 °F) at standard sea-level pressure, and at a lower temperature at high altitude.

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2. 22

   At which temperature do the Celsius and Fahrenheit scales show the same reading?

   A100°B0°C−40°D−32°

   Correct answer: C. −40°

   Using F = (9/5)C + 32 and setting F = C gives C = −40. So −40 °C equals −40 °F.

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3. 23

   One horsepower is approximately equal to:

   A746 wattsB100 wattsC500 wattsD1,000 watts

   Correct answer: A. 746 watts

   One mechanical horsepower is about 746 watts.

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4. 24

   The filament of an ordinary incandescent bulb is usually made of:

   ACopperBNichromeCAluminiumDTungsten

   Correct answer: D. Tungsten

   Tungsten has a very high melting point (about 3,400 °C), so it can glow white-hot without melting.

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5. 25

   A battery converts which form of energy into electrical energy?

   ANuclear energyBHeat energyCChemical energyDLight energy

   Correct answer: C. Chemical energy

   Chemical reactions inside a battery release energy as an electric current.

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