To neutralise completely 20 ml of 0.1 M of aqueous solution of phosphoric acid the volume of 0.1 M aqueous KOH solution required is ??
0.7 g of Na2Co3 .XH2O were dissolved in water and the volume was made to 100mL , 20 mL of this solution required 19.8 mL of N/10 HCl for complete neutralisation, the value of 'x' is
A) 7
B) 3
C) 2
D) 5