A 150 gram piece of ice is removed from a refrigerator at -20c. It is placed in a bowl where it melts and eventually warms to room temperature, 23c. Calculate the amount of heat the sample has gained from the atmosphere.

This is divided into three parts:
Heating up from -20C to 0C;
Melting from ice to water at 0C;
Heating up from 0C to 23C.

Heating up involves the formula Q = mcT and melting involves the formula Q = mL.

m = 150 g in all cases.
c is different for ice and water and both should be given.
T is the change in temperature, you will need to calculate this.
L is the specific latent heat of fusion of water. You should be given this.
Q is the energy and you are calculating it in each case. Add them all up to get the final answer.