Question

Boron and silicon resemble in all respects except:

• A. both form acidic oxides
• B. their hydrides are stable
• C. their chlorides hydrolyse to either respective acids
• D. both form halides which are Lewis acids

Answer 1

The correct option is D both form halides which are Lewis acids

B forms $B{X}_3$ whereas Si forms $Si{X}_4$. $B{X}_3$ is electron deficient and thus a lewis acid. Whereas $Si{X}_4$ has a complete octet and thus not electron deficient.