Q.

The heat extracted out of x gram of water initially at 50°C to cool it down to 0°C is sufficient to evaporate (1000−x) gram of water also initially at 50°C. The value of x (closest integer) is ______.  (Take latent heat of water 2256 kJ/kg.K, specific heat capacity of water 4200 J/kg.K)          [2026]


Ans.

(922)

Given :

According to question: Q1=Q2

(msΔT)1=(msΔT+mL)2

x×4.2×50=(1000-x)[4.2×50+2256]

210x=(1000-x)[2466]

2676x=2466×1000

x=921.52≈922