Question

Which of the following alkaline earth metal can never have more than four molecules of water of crystallisation?

• A. $Sr$
• B. $Ca$
• C. $Be$
• D. $Mg$

Answer 1

The correct option is C $Be$

Option $\left(C\right)$ is correct.

$Be$ can never have more than four molecules of water of crystallisation as it has only four available orbitals in its valence shell. ($Be=2s^{2}2p_x^{0}2p_y^{0}2p_z^0$).

The other elements in II A group may have more than four molecules of water of crystallisation as they have $d$- orbitals as well.