Question

Calculate the value of Z – (X + Y).

$\underline{BF_3}$, $\underline{AlCl_3}$, $\underline{NF_3}$, $\underline{CF_4}$, $\underline{CO_2}$, $\underline{SiF_4}$, $\underline{H_2O}$, $\underline{PCl_5}$

X = Number of species having underlined atom which have maximum covalency equal to their group number of long form of periodic table.

Y = Number of species having underlined atom whose covalency can increase on donation of lone pair.

Z = Number of species having underlined atom whose covalency can increase on acceptance of lone pair.

Answer 1

2

Answer 2

X = 0 (No underlined atom has max covalency = group number). Y = 2 ($NF_3$, $H_2O$ - underlined atoms have lone pairs to donate and increase covalency). Z = 4 ($BF_3$, $AlCl_3$, $SiF_4$, $PCl_5$ - underlined atoms can accept lone pairs to increase covalency). Z - (X + Y) = 4 - (0 + 2) = 2.