Question

A calorimeter contains 0.2kg of water at ${30}^{\circ }C.$ 0.1 kg of water at ${60}^{\circ }C$ is added to it, the mixture is well stirred
and the resulting temperature is found to be ${35}^{\circ }C.$ The thermal capacity of the calorimeter is

• A. 6300 J/K
• B. 1260 J/K
• C. 4200 J/K
• D. None of these

Answer 1

The correct option is B 1260 J/K

Let X be the thermal capacity of calorimeter and specific heat of water = 4200 J/kg-K Heat lost by 0.1 kg of water = Heat gained by water in calorimeter + Heat gained by calorimeter
$\Rightarrow 0.1\times 4200\times (60-35)=0.2\times 4200\times (35-30)+X(35-30)10500=4200+5X\Rightarrow X=1260J/K$