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

Explanation

Heat supplied=Heat used in converting m grams of ice
from `-5^@C to 0^@C` +Heat used in converting 1 gram of ice at
`0^@C to water at 0^@C`
`rArr 420=mxx2100/1000xx5+(1xx3.36xx10^5)/1000`
`rArr 420=mxx10.5+336 :. M=84/10.5=8 grams`