Which alkaline earth metal does not impart a characteristic color to the Bunsen flame: $\text{Mg}$, $\text{Ca}$, $\text{Sr}$, or $\text{Ba}$?

Solution

1. Flame coloration occurs when electrons are excited to higher energy levels and emit light upon returning to the ground state.
2. The energy of the Bunsen flame is insufficient to excite the electrons of $\text{Mg}$ and $\text{Be}$ due to their high ionization enthalpies.
3. $\text{Ca}$, $\text{Sr}$, and $\text{Ba}$ have lower ionization enthalpies and show brick red, crimson, and apple green colors respectively.
4. Hence the answer is (A).