Question

$"N<P<As"$
Above order is incorrect for:

• A. Covalent radii
• B. Size of $M^{3-}$
• C. Acidic nature of $M_2{O}_3$ type oxide
• D. Electropositivity

Answer 1

Answer: (C)

$N,PandAs$ belong to the same group. On moving down the group the atomic radii of atoms increase. Due to the increase in atomic size, the covalent radii and ionic radii also increases. Also with an increase in the size of atom, the nuclear pull on the outermost electrons as well as the ability to attract electrons decreases, resulting in decrease in electronegativity. Hence, electropositivity increases.

$M_2{O}_3$ type of oxides have central atom in +3 oxidation state. On moving down the group the ability of atoms to loose electrons increases due to the weakening of nuclear pull on the outermost electrons, hence, basicity increases. Thus, the acidic nature of oxides decreases.