Which of the following is correct according to the Lewis acid-base concept ?

Options

A. All positively chages ions are bases.
B. All negatively charged ions are acids.
C. A molecule in which the central atom has vacant d-orbitals avaliable acts as an acid.
D. Species in which the central atom has complete octet cannot act as acid.

Answer

C

Explanation

`SnCI_(4)` is a Lewis acid because the tin atom can expend its valence shell by utilizing vacant d-orbitals. All positively charged ions are not Lewis bases, e.g., `Cu^(2+)` and `Ag^(+)` ions cannot act as Lewis bases but not Lewis acids, e.g., `CI^(-)` and `CN^(-)` ions. A species in which the central atom has complete octet can act as an acid provided it is `pi`-bonded to highly electronegative atom, e.g., `CO_(2)`.