. Which of the following is a Lewis acid
Sol: ||| Lewis Acid accepts pairs of electrons whereas Lewis base donates pairs of electrons.
B(CH3)3 is a 6 e- species - which means that the central atom has an incomplete octet. It is an electron deficient molecule and thus can accept electrons. Hence, it is considered to be a Lewis Acid
In the case of PH3 P has a lone pair and thus P can donate. Hence, it is considered to be Lewis base.
NaH: Na can donate lone pair, thus acting as Lewis base.