Statement (1) is correct. Steam contains more heat than the same amount of water at the same temperature. When steam condenses, it gives out this extra latent heat and causes severe burns. Statement (2) is correct. The combination of low specific heat (requires less temperature to react) and high thermal conductivity (rapid transfer of heat) is the most desirable for a cooking pot.

• Greater is the mass of the body, more is the temperature required to heat it.
  • Nature of the substance of the body (metal, non-metal) also affect the quantity of heat required to raise the temperature of a body.
  • Volume and shape of a body do not affect the quantity of heat require to raise the temperature of a body.

Statement (1) is incorrect. At night the sea water cools down more slowly than the land and the cool air from the land moves towards the sea. This is called the land breeze, not night breeze. Statement (2) is incorrect. Air being a bad conductor of heat compared to the metallic sphere which is a good conductor, the maximum heat is utilized in expanding the metallic part. In case of solid, the change in radius will be greater due to the metallic substance present in it.

Statement (1) is correct. Yes, the burner of hot air balloon uses propane gas to heat up the air in the envelope to move the balloon off the ground and into the air because it is a colourless, odourless and non-toxic gas. It is supplied commercially with an added odorant (usually ethylmercaptan) to assist detection by smell. Statement (2) is incorrect. Yes, hypothalamus balances body temperature, but it is present in brain. Hypothalamus is also called as 'balancing organ'.

Statement (1) is incorrect. Stainless steel pans are usually provided with copper bottoms because copper is a better conductor of heat than the stainless steel. Statement (2) is correct. The process of conversion of water into vapours without reaching the boiling point is called evaporation.

(i) Statement (1) is correct. Yes, thermophilic organisms are those organisms, which are adapted to living in high temperatures. (ii) Statement (2) is incorrect. Pasteurization of milk takes place at 60^oC. At this temperature, it limits the growth of milk borne infectious diseases.

Wood, glass and plastic are bad conductors of heat. Iron is a metal, which is a good conductor of heat. So ice kept in the iron box will melt the fastest.

Statement (1) is correct. Oil present in soup doesn't mix with water, and floats on top of water, and usually makes a very thin layer, covering all the water and it prevents the water molecules from evaporating. Statement (2) is incorrect. ‘Heat capacity’ means the amount of heat required to reach at its boiling point. The intermolecular bonds of vegetables and oil require a lot of heat to break.

Statement (1) is wrong. Clinical thermometer has low heat capacity, i.e. mercury (present in thermometer) has less specific heat to warm up. Therefore, thermometer measures even the small change in body temperature. Statement (2) is correct. Yes, leaching is the process of extracting minerals from a solid by dissolving them in a liquid. Uranium and gold are extracted from their ores by chemical leaching.

(i) Statement (1) is correct. These winds are called trade winds. These winds (also called trades) are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere. (ii) Statement (2) is incorrect. The S.I. unit of heat is Joule. Newton is the S.I. unit of force.

Statement (1) is correct. Mercury is the only liquid in which conduction is possible due to its low specific heat. Statement (2) is incorrect. Black bodies are good radiators and good conductors of heat.

(i) Statement (1) is incorrect. The air in a hair dryer is heated by radiation. The air is heated by a hot, glowing coil of wire that emits radiation. (ii) Statement (2) is correct. If air were a good conductor of heat, at night time the earth would be considerably cooler because all the heat of earth is escaped in the space through air as a medium.

Statement (1) is wrong. Rug or carpet acts as an insulator. It does not conduct the heat of the floor to the feet. Statement (2) is correct. Convection is the flow of heat through a bulk, macroscopic movement of matter from a hot region to a cool region.

The flame heats the pan by radiation, heat is transferred through the pan by conduction, and heat rises through the oil by convection.

Statement (1) is incorrect. The boiling point of vegetable oil is high as compared to that of water. Statement (2) is incorrect. As boiling point of water is low, it changes into water vapours and increases the density of oil. Statement (3) is correct. The water droplets vaporise and leave the oil behind in the pan.