how much heat must be absorbed by a 500 g pot of water to raise the temperature from 20 degree C to 30 degree C?

Answer 1

If you don't include the energy that has to be added to the pot, the amount that has to be added to the water is M*C*(T2 - T1) = 5000 calories

C is the specific heat of water,
1.00 cal/(g degC)

You must have seen this formula before, in your text or class notes.