Question

In the reaction $I_2+I^{-}\rightleftharpoons I_3^{-},$
Which of the following acts as a Lewis base is:

• A. $I_2$
• B. $I^{-}$
• C. $I_3^{-}$
• D. None of these

Answer 1

The correct option is B $I^{-}$

Lewis Concept (Electronic concept) :
Lewis acid - species which can accept an electron pair with the formation of a coordinate bond.
Lewis base - species which has a lone pair of electrons available for donation.

Here $I^{-}$ is giving electron pair to $I_2$​ molecule. Therefore $I_2$​ is a lewis acid and $I^{-}$ is a lewis base.