On dissolving 1 mole of each the following acids, in 1 litre water, the acid which does not give a solution of strength 1N

1) HCl – basicity = 1

2) $\text{HC}l{\text{O}}_4$- perchloric acid basicity = 1

3) ${\text{HNO}}_3$- Nitric acid basicity = 1

4) ${\text{H}}_3{\text{PO}}_4$ Phosphoric acid basicity = 3

So, phosphoric acid does not give 1N solution.