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

1mole dissolved in 1l given 1N solThis is possible only when valency of the acid=1HCl, HNO3,HClO4......  monobasic ∴1M=1NBut H3PO4 is tribasic ∴1M≠1NThus 1 mole of H3PO4  dissolved in one lit gives 1M sol. but not 1N sol