JAMB Physics 2019 Paper

Concept:Latent heat is the heat energy absorbed or released per unit mass during a change of state.Explanation:Let $L$ be the latent heat and $m$ be the mass of the substance.The heat energy absorbed or released is given by:$$H = mL \quad \Rightarrow \quad L = \frac{H}{m}$$Heat energy $H$ is measured in joules ($\mathrm{J}$).Mass $m$ is measured in kilograms ($\mathrm{kg}$).Therefore, the unit of latent heat is:$$L = \frac{\mathrm{J}}{\mathrm{kg}} = \mathrm{J\,kg^{-1}}$$From the list, only unit V, $\mathrm{J\,kg^{-1}}$, matches this result.Answer:Option D — V.