The electronic configurations of three elements, A, B and C are given below. Answer the questions 14 to 17 on the basis of these configurations.
A 1s2 2s2 2p6
B 1s2 2s2 2p6 3s2 3p3
C 1s2 2s2 2p6 3s2 3p5
Stable form of A may be represented by the formula :
The last orbital of the element A has completed octet (i.e. 8 electrons in the last energy shell (orbital s and p)) so it is in a stable state.