# Given below are two statements:  Assertion (A): Evaporation can occur at any temperature, whereas the boiling point of a liquid depends on external pressure. Reason (R): Evaporation happens from the surface of a liquid at all temperatures, while boiling occurs at a specific temperature determined by external pressure.   1. Both (A) and (R) are true and (R) is the correct explanation of (A). 2. Both (A) and (R) are true but (R) is not the correct explanation of (A). 3. (A) is true but (R) is false. 4. Both (A) and (R) are false.

Subtopic:  Calorimetry |
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Given below are two statements:
 Assertion (A): The emissive power of a body at a temperature T (in K) is directly proportional to T4. Reason (R): Good emissive power of a body means the body is a good radiator.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 Both (A) and (R) are false.

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Given below are two statements:
 Assertion (A): The volume of water increases when its temperature is decreased below or increased above $$4^\circ \text{C}.$$ Reason (R): The density of water is highest at $$4^\circ \text{C}.$$

 1 Both (A) and (R) are True and (R) is the correct explanation of (A). 2 Both (A) and (R) are True but (R) is not the correct explanation of (A). 3 (A) is True but (R) is False. 4 Both (A) and (R) are False.
Subtopic:  Thermal Expansion |
72%
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Given below are two statements:
 Assertion (A): Water kept in an open vessel will quickly evaporate on the surface of the moon. Reason (R): The temperature at the surface of the moon is much higher than the boiling point of water.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 Both (A) and (R) are false.

Subtopic:  Calorimetry |
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Given below are two statements:
 Assertion (A): At room temperature water does not sublimate from ice to steam. Reason (R): The critical point of water is much above room temperature.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 Both (A) and (R) are false.

Subtopic:  Calorimetry |
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Given below are two statements:
 Assertion (A): With rise in temperature, time period of a pendulum remains same. Reason (R): Time period is not dependent on temperature.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 Both (A) and (R) are false.

Subtopic:  Thermal Expansion |
83%
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Given below are two statements:
 Assertion (A): A body that is a good radiator is also a good absorber of radiation at a given wavelength. Reason (R): According to Kirchhoff's law, the absorptivity of a body is equal to its emissivity at a given wavelength.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 Both (A) and (R) are false.

78%
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Given below are two statements:
 Assertion (A): In a pressure cooker the water is brought to a boil. The cooker is then removed from the stove. Now on removing the lid of the pressure cooker, the water starts boiling again. Reason (R): The impurities in water bring down its boiling point.

 1 Both (A) and (R) are True and (R) is the correct explanation of (A). 2 Both (A) and (R) are True but (R) is not the correct explanation of (A). 3 (A) is True but (R) is False. 4 Both (A) and (R) are False.
Subtopic:  Calorimetry |
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A vessel containing water is heated from the top by means of a heater, just above the water surface. Assume that the temperature of the water was just above $$0^\circ\mathrm{ C},$$ in the beginning. The temperature $$(\theta_A)$$ at the bottom is measured as a function of time. Which of the following shows the correct plot?

1. a
2. b
3. c
4. d
Subtopic:  Convection |
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Two different liquids of the same mass are kept in two identical vessels which are placed in a freezer that extracts heat from them at the same rate causing each liquid to transform into a solid. The schematic ﬁgure below shows the temperature $$T$$ versus time $$t$$ plot for the two materials. We denote the speciﬁc heat in the liquid states to be $$C_{L_1}$$ and $$C_{L_2}$$ for materials 1 and 2 respectively and latent heats of fusion  respectively.

Choose the correct option:
 1 $$C_{L_1}>C_{L_2}~\text{and }U_1C_{L_1}~\text{and }U_1U_2$$ 4 \(C_{L_1}
Subtopic:  Calorimetry |
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