Question
Among $$A{l_2}{O_3},Si{O_2},{P_2}{O_3}\,{\text{and}}\,S{O_2}$$ the correct order of acid strength is
A.
$$A{l_2}{O_3} < Si{O_2} < S{O_2} < {P_2}{O_3}$$
B.
$$Si{O_2} < S{O_2} < A{l_2}{O_3} < {P_2}{O_3}$$
C.
$$S{O_2} < {P_2}{O_3} < Si{O_2} < A{l_2}{O_3}$$
D.
$$A{l_2}{O_3} < Si{O_2} < {P_2}{O_3} < S{O_2}$$
Answer :
$$A{l_2}{O_3} < Si{O_2} < {P_2}{O_3} < S{O_2}$$
Solution :
As the size increases the basic nature of oxides changes to acidic nature i.e., acidic nature increases.
$$\mathop {S{O_2} > {P_2}{O_3}}\limits_{Acidic} > \mathop {Si{O_2}}\limits_{Weak\,acidic} > \mathop {A{l_2}{O_3}}\limits_{Amphoteric} $$
$$\,S{O_2}\,{\text{and}}\,{P_2}{O_3}$$ are acidic as their corresponding acids $${H_2}S{O_3}\,{\text{and}}\,{H_3}P{O_3}\,$$ are strong acids.