Heat and Thermodynamics (Physics) Part-I

In winter, if we touch a log of wood and a rod of iron, we feel that rod of iron is cold. It is because of the fact that in comparison to wood, iron is a good conductor of heat.

When both the metal and the wood are at the same temperature, heat will flow from iron. Similarly, when we touch wood, a poor conductor, heat does not flow from it. Hence iron rod will feel colder as compared to wood.

There is a direct relation between the atmospheric humidity and temperature. The ability of air to assume water vapour depends on its temperature. Thus, if temperature of air is increased then automatically its ability to hold water vapour will also be increased.

Dew is not formed in the night of strong wind as due to strong wind the rate of evaporation is fast. Thus, the particles of the dew tend to evaporate.

Air conditioner and Air-cooler both maintains temperature and the motion of air. But the Air conditioner also having the ability to maintain humidity, while air cooler doesn't have the ability to maintain humidity. Thus it is clear that option (b) is not true.

Air conditioner and Air-cooler both maintains temperature and the motion of air. But the Air conditioner also having the ability to maintain humidity, while air cooler doesn't have the ability to maintain humidity.

The cooling by a desert cooler is based on evaporative cooling. These coolers are also known as swamp coolers.

Most of the air conditioners use compressed gas, which can cool the room or other places.

The wet clothes will dry earliest at minimum humidity & maximum temperature. Thus according to options given in the question, option (d) will dry the wet clothes earliest.

If salt is added to water then the boiling point of water will increase. This happens as the boiling point is the temperature at which the vapor pressure of solvent becomes equal to the external atmospheric pressure.

Similarly it also decreases the freezing point, which in turn will interfere with the frozen solution's crystal structure. That means the temperature will have to be colder to overcome it and freeze the mixture.

If salt is added to water then the boiling point of water will increase. This happens as the boiling point is the temperature at which the vapor pressure of solvent becomes equal to the external atmospheric pressure.

Similarly it also decreases the freezing point, which in turn will interfere with the frozen solution's crystal structure. That means the temperature will have to be colder to overcome it and freeze the mixture.