Which of the following similarities between beryllium and aluminium are genuine?

ABoth hydroxides dissolve in excess sodium hydroxide
BThe chlorides of both are electron deficient and attain higher coordination through chloride bridges
CBoth carbides give ethyne on hydrolysis
DBoth metals are rendered passive by concentrated nitric acid

Answer: A, B, D

Be(OH)2 and Al(OH)3 are amphoteric, both metals form protective oxide films in conc. HNO3, and BeCl2 (chain) and AlCl3 (as

Al X_{2} Cl X_{6}

) use bridging chlorides. The carbides

Be X_{2} C

and

Al X_{4} C X_{3}

contain

C X^{4 -}

and give methane, not ethyne.