Question

The group to which representative elements belong is signified by :

• A. the number of electrons presents in the outermost shell
• B. the number of electrons presents in the penultimate shell
• C. the number of electrons presents in the outermost shell and penultimate
• D. none of these

Answer 1

The correct option is A the number of electrons presents in the outermost shell

The group number of a representative element is given by sum of electrons in outermost shell. Eg: N belongs to $V$ group. Its configuration is $1s^{2}2s^{2}2p^3$

$\therefore$Group number$=2\left(2s\right)+3\left(2p\right)=5$

i.e., group $V$

Hence answer is option A.