$A$ coordinate bond is formed when an atom in a molecule has

In the reaction $I_2 + I^{-} \to I_3^-$,the Lewis base is

Which of the following is the correct representation of the reaction when $BF_3$ reacts with ammonia?
$(i)$ $F_3B + :NH_3 \rightarrow [F_3B \leftarrow :NH_3]$
(ii) $F_3B + :NH_3$ $\rightarrow [F_3B$ $\rightarrow :NH_3]$

Select the species which is planar at nitrogen.

In the reaction $NH_3 + BF_3 \rightleftharpoons NH_3 \to BF_3$,$BF_3$ is

Dative bond is present in