Certain amount of heat is given to 100 g of copper to increase its temperature by `21^@C`. If same amount of heat is given to 50 g of water, then the rise in its temperature is (specific heat capacity of copper ` = 400 J kg^(-1) K^(-1)` and that for water ` = 4200 J kg^(-1) K^(-1))`

Options

A. `4^(@)C`
B. `5.25^(@)c`
C. `8^(@)C`
D. `6^(@)C`

Answer

A

Explanation

The amount of heat supplied is given by the relation.
`Q=mcDeltaT`
Here, m = 100g=0.1g, c=400 J/kg-K,
`DeltaT`=21 K for copper.
Thus, Q = `0.1 xx 400 xx21=840`J
Hence, `840=0.05xx4200xx DeltaT rArr DeltaT=4^(@)`C