If 1.8 L of water is added to 2.5 L of a 7.0 M KOH solution, what is the molarity of the new solution?

2.8 M

4.1 M

5.0 M

9.7 M

Molarity = (number of moles of that substance) / (Volume of solution in litres)

7 = (number of moles of HCl) / 0.05

Thus,

Number of moles of HCl = 7 x 0.05 = 0.35

The number of moles of HCl will remain unchanged.

Now, for new solution,

0.35 = 0.35 / (New volume of solution in litres)

Thus,

New volume = 1 litre

Thus, amount of water added = 1 - 0.05 litre = 5.0 M