The correct option is A 2 M
Let M be the molarity of the final solution.
Conserving the total moles before and after mixing:
M1V1+M2V2=MV
where M2 and V2 are the molarity and volume of 1 M solution.
M1 and V1 are the molarity and volume of 6 M solution.
So,
(M×1000)=(1×200)+(6×300)
On solving, molarity = 2 M
Since HNO3 dissociates to H+ ion and NO−3 ion
Concentration of H+ ions=2 M