Answer
$0.871\text{ kJg}^{-1}$
Work Step by Step
Molar mass of $Ca(OH)_{2} =74 \text{ g/mol}$
Enthalpy change occurred to convert one mole of $Ca(OH)_{2}$ to $CaO$ is $64.50\text{ kJmol}^{-1}$
Hence for $1$ g of $Ca(OH)_{2} = 64.50 \text{ kJmol}^{-1}/74\text{ gmol}^{-1} = 0.871\text{ kJg^{-1}}$
