Specific heat is the amount of heat required to raise the temperature of a unit mass of a substance by a unit degree. It is usually expressed as J/g C
In this case :
165.2 J of heat is required to raise the temperature of 1 mole of heptane by 1 C
1 mole of heptane (C7H16) = 100 g
Specific heat of heptane = 165.2/100 = 1.652 J/g C