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

Options

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

Answer

B

Explanation

Let the thermal capacity of calorimeter is C, cal/°C then
`200(T-30)+c(T-30)=100(60-T)or,1000+5c=2500`
`or,5c=1500,c=300cal//K`
`=300(4.2)J//K,=1260J//K`