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. |
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. |
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. |
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. |
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. |
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. |
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. |
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. |
1. | \(C_{L_1}>C_{L_2}~\text{and }U_1<U_2\) |
2. | \(C_{L_2}>C_{L_1}~\text{and }U_1<U_2\) |
3. | \(C_{L_1}<C_{L_2}~\text{and }U_1>U_2\) |
4. | \(C_{L_1}<C_{L_2}~\text{and }U_1<U_2\) |