Question

Which among the following statements are correct?
(i) Carbon monoxide is neutral whereas $S{0}_3$ is acidic
(ii) Potassium oxide is basic whereas nitrous oxide is acidic
(iii) Aluminium and zinc oxides are amphoteric
(iv) Sulphur trioxide is acidic whereas phosphorus pentoxide is basic
(v) Carbon dioxide is netural whereas sulphur dioxide is amphoteric

• A. (ii) and (iii)
• B. (i) and (iv)
• C. (i) and (iii)
• D. (ii) and (iv)
• E. (iii) and (v)

Answer 1

Answer: (C)

(i) Carbon monoxide is neutral and $S{O}_3$ is acidic.
(ii) Aluminium and zinc oxides are amphoteric, so aluminium and zinc oxides react with both as acid and base.
$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$ (with acid)
$A{l}_2{O}_3+2NaOH+3H_{2}O\to 2NaAl{(OH)}_4$ (with base)
$ZnO+H^{+}\to Z{n}^{2+}+H_{2}O$ (in acid)
$ZnO+2O{H}^{-}+H_{2}O\to {[Zn{(OH)}_4]}^{2-}$ (in base)
Hence, (i) and (ii) are correct.