Mass of ice m = 200 g
Specific latent heat of fusion of ice L = 336 Jg^-1
Heat required Q = m L
= 200 x 336
Q = 67,200 J

Mass of iron m = 5 kg
Initial temperature t₁ = 30°C
Final temperature t₂ = 130°C
Rise is temperature \(\triangle \)t₂ = (t₂ - t₁) = 130 - 30 = 100°C
Specific heat capacity of iron c = 483 Jkg^-10C^-1
Q = m x c x \(\triangle \)t
= 5 x 483 x 100
= 2,41,500 J

(i) When steam hits our skin, it condenses to water and then cools down to the temperature of skin.
(ii) Now, the energy released will be due to latent heat and fall in temperature.
(iii) Whereas when boiling water hits our skin, there is no phase transition but only fall in temperature and the heat transferred to skin will be only due to cooling.
(iv) Also, the loss of energy that is released from steam hitting our skin occurs quickly and in a small localized area, therefore causing damage to our cells.

The process of transfer of heat in solids from a region of higher temperature to a region of lower temperature without the actual movement of molecules is called conduction.

The minimum possible temperature is 0K. There is no limit to maximum temperature.

1 Calorie = 4.186 J
= 4.2 J

The amount of heat energy required to raise the temperature of 1 g water by 1⁰C is called one calorie.

1. Mass of the body
2. Change in temperature of the body
3. Nature of the material of the body.

Mass of water = 25 grams
\(\triangle\)T = (100^oC - 0^oC) =100^oC
C = 4.18 J/g^oC
Heat energy required Q = M x C x \(\triangle\)T
= 25 x 4.18 x 100^oC
= 10450 J

Specific latent heat of ice is very high (i.e.) 336 J/g.
1. Due to high specific latent heat of ice, snow on mountains do not melt as a whole, but melts gradually into water with the heat of the sun. If the specific latent heat of ice would not have been so high, all the snow would have melted very quickly and there would have been floods in the rivers.
2. All the water in lakes and ponds in cold places do not freeze all at the same time. If freezes slowly and keeps the surrounding moderate.
3. Drinks are cooled more effectively by ice pieces at 0⁰C and not by water at 0⁰C. This is because 1 g of ice takes away 336 J of heat from the drink to melt into water at 0⁰C.