How much water should be added to 200 c.c of seminormal solution of NaOH to make it exactly decinormal?

How much water should be added to 100 ml of 1MH_(2)SO_(4) solution to make it exactly 0.1 N ?

20 mL of a solution of sulphuric acid neutrlise 21.2 mL of 30 % solution of sodium carbonate. How much water should be added to 100 mL of this solution to bring down its strength to decinormal ?

The amount of water to be added to 100 c.c. of 1 normal HCl solution to make it decinormal is -

Calculate the volume of water to be added to 400 ml of seminormal HCl solution to make it decinormal