Heat capacity of ball = 50 J⁰C^-1
Heat lost Q = 2000 J
Fall in temperature t = ?
Heat capacity = \(\frac { Q }{ t } \)
50 = \(\frac { 2000 }{ t } \)
t = \(\frac { 2000 }{ 50 } \)
t = 40⁰C

Heat absorbed Q = 1,68,000 J
m = 2kg
Initial temperature t₁ = 30°C
Let final temperature t₂ = x⁰C
Rise is temperature \(\triangle \)t = (t₂ - t₁)
= (x- 30)⁰C
Specific heat capacity of water C = 4200 J kg^-1°C^-1
We know that Q = m x c x \(\triangle \)t
1,68,000 = 2 x 4200 x (x - 30)
x - 30 = \(\frac { 1,68,000 }{ 2\times 4200 } \)
\(\)x - 30 = 20
x = 30 + 20
= 50°C
So, the final temperature of water = 50°C

Mass of lead m = 115 g
Heat required Q = 2875 J
Specific latent heat of lead L = ?
We know that Q = m L
L = \(\frac { Q }{ m } =\frac { 2875 }{ 115 } \)
= 25 Jg^-1

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.

100 g of water = 90^o C
600 g of water \(=20^{\circ} \mathrm{C} \times 6=120^{\circ} \mathrm{C}\)
700 g of water total temperature \(=90^{\circ}+120^{\circ} \mathrm{C}=210^{\circ} \mathrm{C}\)
The final temperature of water is \(=210^{\circ} \mathrm{C} / 7=30^{\circ} \mathrm{C}\)
(OR)
Final temperature of a mixture (t) = ?
\(t =\frac{\left(m_{1} c_{1} t_{1}\right)+\left(m_{2} c_{2} t_{2}\right)}{\left(m_{1} c_{1}\right)+\left(m_{2} c_{2}\right)}  \)
\(=\frac{(100 \times 4.18 \times 90)+(600 \times 4.18 \times 20)}{(100 \times 4.18)+(600 \times 4.18)}  \)
\(=\frac{37620+50160}{418+2508}=\frac{87780}{2926}  \)
\(t =30^{\circ} \mathrm{C}\)

Latent heat is the amount of heat energy absorbed or released by a substance during a change in its physical state without any change in its temperature.

The earthen pot is made up of soil. Soil is the bad conductor of heat. So the pot has minute pores. The least amount of water is leaked through the pores. It prevents to heat does not enter into the pot, so the water is remain cool.