(a) Why does an aqueous solution of an acid conduct electricity ?
(b) How does the concentration of hydrogen ions `[H_(3)O]^(+)` change when the solution of an acid is diluted with water ?
(c ) Which has a higher pH value , a concentrated or dilute solution of hydrochloric acid ?
(d) what happens when hydrochloric acid reacts with (i) sodium bicarbonate placed in a test tube ?
(ii) zinc metal in a test tube ?

Explanation

(a) An awueous solution of an acid conducts electricity because in wate, an acid (e.g.HCl) dissociated to give ions. Since the current is carried by the movement of ions, an awueous solution of acid conducts electricity.
(b) Upon dilution, more of acid dossociates into ions. Therefore, concentration of `[H_(3)O]^(+)` ions increases upon dilution.
(c ) Although more `[H_(3)O]^(+)` ions are formed upon dilution, but the number of ions per unit volume decrease. Therefore pH will increase upon dilution.
(d) (i) Carbon dioxide gas would evolve accompanied by drisk effervescene.
`NaHCO+_(3)(s) +HCl(aq)to NaCl(aq)+CO_(2)(g)+H_(2)O(aq)`
(ii) Hydrogen gas would evolve accompanied by brisk effervescent.
`Zn(s)+2HCl(aq)toZnCl_(2)(aq)+H_(2)(g)`