What is common between $NH_3$ and $PH_3$?

$AlCl_3$ exists as a dimer because....

Which of the following compounds has a coordinate (dative) bond?

Which of the following contains a coordinate covalent bond?

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) $F_3B + :NH_3$ $\rightarrow [F_3B$ $\rightarrow :NH_3]$

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