Question
Physics Question on specific heat capacity
The heat of combustion of a substance is :
A
Always positive
B
Always negative
C
Numerically equal to the heat of formation
D
Unpredictable
Answer
Always negative
Explanation
Solution
Heat of combustion of a substance is always negative as it is the amount of heat evolved (i.e. decrease in enthalpy) when one mole of the substance is completely burnt in air or oxygen.