\(H _2 \ddot{ O :} \longrightarrow \text { Lewis base }\)
\(BF _3 \longrightarrow \text { Lewis acid }\)
\(\ddot{ :O :}H \longrightarrow \text { Lewis base }\)
\(\ddot{ N } H _3 \longrightarrow \text { Lewis base }\)
$A = NH_4Cl$; $ B = CH_3COONa$; $ C = NH_4OH$; $D = CH_3COOH$