Chemistry

Problem

Consider the following table

Compounds<br>(X are monovalent surrounding atoms)	Central atoms(A to D) belong to group	Characteristics of compounds	Number of lone pair(s) at central atom
(i) $AX_{n_1}$	16	Planar and polar	$m_1$
(ii) $BX_{n_2}$	15	Trigonal pyramidal	$m_2$
(iii) $CX_{n_3}$	14	Zero dipole moment	$m_3$
(iv) $DX_{n_4}$	13	All $X - D - X$ bond angle are $120^\circ$	$m_4$

Then calculate value of expression

\left| \frac{n_1 + n_2 + n_3 + n_4}{m_1 + m_2 + m_3 + m_4} \right|^2