Which of the following statements is correct about an aqueous solution of an acid and of a base?
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) Lower the pH, stronger the base
(iv) Lower the pH, weaker the base
(i) and (iii)
(ii) and (iii)
(i) and (iv)
(ii) and (iv)
Steps: Higher pH = more basic → acids are weaker at higher pH (ii). Lower pH = more acidic → bases are weaker at lower pH (iv). So (ii) and (iv) true.