question_answer 1)

Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Why?

Answer:

Beryllium and magnesium being smaller in size possess high ionisation enthalpies in comparison to other alkaline earth metals. Therefore both require large amount of energy for excitation of electrons to higher energy shells. Since, so much of energy is not available, these metals do not impart any colour to flame.