Q: Steam at 100°C is passes into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 15°C till the temperature of the calorimeter and its contents rises to 80°C. The mass of the steam condensed in kg is

(a)0.130

(b) 0.065

(c) 0.260

(d) 0.135

Ans: (a)

Sol: Heat required

$\large Q_1 = (1.1+0.02)\times 10^3 \times 1 \times (80-15)$

Q_{1} = 72000 cal

Let mass of steam condensed is m kg , when heat is given .

Heat given $\large Q_2 = ( m \times 540 \times 10^3 ) + m \times 1 \times 10^3 \times (100-80)$

On applying , $\large Q_1 = Q_2 $

we get , m = 0.130 kg