Practice MCQ Questions and answers on Physics-GK

31

Absolute Zero is defined as

A) The temperature at which all molecular motion ceases B) At which water boils at 298K C) At which liquid Helium boils D) At which the volume becomes zero

Discuss

Answer & Solution

Answer: Option A

Solution:

Absolute Zero is defined as temperature at which all molecular motion ceases.

32

At what temperature (in degree Celsius), the numerical values on Celsius and Fahrenheit scales become equal?

A) –40 B) 40 C) 273 D) –273

Discuss

Answer & Solution

Answer: Option A

Solution:

Celsius and Fahrenheit are the same at – 40 degrees since the scales converge.

33

At what temperature (in Fahrenheit) pure water freezes?

A) 32 B) 0 C) 48 D) 37

Discuss

Answer & Solution

Answer: Option A

Solution:

32^oF is the temperature at which fresh water freezes is called the freezing point. The freezing point is the temperature at which a liquid turns to a solid.

34

On the Kelvin scale, the melting point of ice is

A) 373K B) 100K C) 273K D) 0 K

Discuss

Answer & Solution

Answer: Option C

Solution:

The melting point of ice on Kelvin scale is 273 K.

35

The temperature which has the same reading on both Fahrenheit and Celsius scales is

A) 40° B) –40° C) 0° D) 32°

Discuss

Answer & Solution

Answer: Option B

Solution:

The temperature which has the same reading on both Fahrenheit and Celsius scales is –40°.

36

A gas thermometer is more sensitive than a liquid thermometer because a gas :

A) Is lighter than liquid B) Expands more than a liquid C) Is easy to obtain D) Does not change state easily

Discuss

Answer & Solution

Answer: Option B

Solution:

Since gas expands much more than liquid on changing the temperature. Thus a gas thermometer is more sensitive than liquid thermometer as gas can expand more even in very small change in temperature. So the measurement has to be precised.

37

What is the SI unit of temperature?

A) Kelvin B) Joule C) Celsius D) Fahrenheit

Discuss

Answer & Solution

Answer: Option A

Solution:

Kelvin is the base unit of temperature in the SI system (International System of Units).

38

Earliest thermometer was developed by

A) Celsius B) Fahrenheit C) Kelvin D) Galileo

Discuss

Answer & Solution

Answer: Option D

Solution:

Thermoscopes were the earliest types of thermometers and they only showed changes in temperature but didn't show numerical values. One of the first thermoscopes was developed by Italian inventor, Galeleo Galilei in 1593.

39

The absolute zero is a temperature at which ________

A) Molecular motion in a gas would cease B) Water freezes C) All gases become liquid D) All gases become solid

Discuss

Answer & Solution

Answer: Option A

Solution:

The absolute zero is a temperature at which molecular motion in a gas would cease.

40

Ice cubes are added to a glass of pure water and a glass of pure alcohol. The ice would be

A) At a higher level in water B) At a higher level in alcohol C) At the same level in both D) Floating in alcohol and sinking in water

Discuss

Answer & Solution

Answer: Option A

Solution:

Density of water is approx 1g/ml; Density of Ice is approx 0.93g/ml; and Density of 100% pure ethanol is 0.79g/ml. So the density of ice cubes is lesser than water, but higher than alcohol. So it will float in water, but sink in alcohol. This can also be put as: The ice cube will float higher in water as compared to alcohol.