Which group 13 element forms a hydride that is electron-deficient?
B forms B₂H₆, an electron-deficient hydride with three-center two-electron bonds, unlike Al (AlH₃, polymeric), Ga, or In, which form less distinct hydrides.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev