A piece of ice (heat capacity `=2100 J kg^(-1) .^(@)C^(-1)` and latent heat `=3.36xx10^(5) J kg^(-1)`) of mass m grams is at `-5 .^(@)C` at atmospheric pressure. It is given 420 J of heat so that the ice starts melting. Finally when the ice . Water mixture is in equilibrium, it is found that 1 gm of ice has melted. Assuming there is no other heat exchange in the process, the value of m in gram is

Options

A. 4
B. 6
C. 8
D. 10

Answer

C

Explanation

`[m xx 2100 xx 5+1 xx 3.36 xx 10^(5)] xx 10^(-3) = 420`
where m is in grams.
or `m xx 2100 xx5xx 10^(-3) + 336 = 420`
or `m xx 2100 xx 5 xx 10^(-3) = 84 or m = (84)/(2100 xx 5 xx 10^(-3)) = 8g`