The formula of an oxyacid of phosphorus is $H_3PO_4$. It is a

Boron halides are Lewis acids because.....

Boron halides behave as Lewis acids because of their nature.

Which of the following boron compounds is the hardest?

Sodium borate on reaction with $H_2SO_4$ (conc.) and $C_2H_5OH$ gives a compound '$A$' which burns with a green flame. The compound '$A$' is

In diborane $(B_2H_6)$,the number of $2$-centre-$2$-electron bonds and $3$-centre-$2$-electron bonds respectively are: