Ionization enthalpy decreases down the group due to gradual increases in atomic size .However the deviation is observed as we move from

Options

A. `Sb` to`Bi`
B. `As` to`Sb`
C. `P` to`As`
D. `N` to`P`

Answer

1

Explanation

Both `2^(nd)`and `3^(rd)`ionization enthlpies of `Bi` are higher than those of `Sb`
`{:(ul("Ionization enthalpy kJ/mol"),,ul(Sb " "Bi)),(Delta_(i)H_(2),,"1595 1610"),(Delta_(i)H_(3),,"2443 2446"):}`
This is due to the presence of poorest shielding f eletrons in the core of `Bi`.