AP EAPCET 19th May 2023 Shift 1 Solved Paper

The alkaline earth metals are $\mathrm{Be}$, $\mathrm{Mg}$, $\mathrm{Ca}$, $\mathrm{Sr}$, $\mathrm{Ba}$ and $\mathrm{Ra}$.Densities of the first four members are: $\mathrm{Be} = 1.85\ \mathrm{g\,cm^{-3}}$, $\mathrm{Mg} = 1.74\ \mathrm{g\,cm^{-3}}$, $\mathrm{Ca} = 1.55\ \mathrm{g\,cm^{-3}}$, $\mathrm{Sr} = 2.64\ \mathrm{g\,cm^{-3}}$.Comparing these values, $\mathrm{Ca}$ has the smallest density, which is lower than even that of $\mathrm{Be}$ and $\mathrm{Mg}$.This is due to the comparatively large atomic size and relatively weak metallic bonding of $\mathrm{Ca}$ in its crystal lattice, which gives it an unusually open structure.Hence the alkaline earth metal with the lowest density is $\mathrm{Ca}$.