Heat produced on burning 5gm of a fuel raises the temperature of 1 kg of H₂O from 20^oC – 60^oC. If the specific heat of H₂O is 4.2J/g^oC, calculate the calorific value of the fuel?

76 Give some examples for renewable and non-renewable sources? 77 Which is the known biogas? 79 Explain greenhouse effect. 80 Why does the interior of a car parked in the sun become hot?