Question

Those elements impart colour to the flame on heating in it, the atoms of which require the low energy of the ionization (i.e., absorb energy in group visible region of the spectrum). The elements of which of the following groups will impart colour to the flame?
(a) 2 (b) 13 (c) 1 (d) 17

Answer 1

Answers: (a) 2 and (c) 1

The element of group 1 (alkali metals) and group 2 (alkaline earth metals) have 1 and 2 electrons respectively in their valence shells and hence have low ionisation energies In other words, elements of group 1 and 2 impart colour to the flame.