d
(d) With decrease in size from \(Al\) to \(S\) the basic nature of oxide decrease and acidic nature increases. \(A{l_2}{O_3} < Si{O_2} < {P_2}{O_3} < S{O_2}\) \(A{l_2}{O_3}\) is amphoteric, \(Si{O_2}\) is slightly acidic whereas \({P_2}{O_3}\) and \(S{O_2}\) are the anhydrides of acids \({H_3}P{O_3}\) and \({H_2}S{O_3}\).