What is the molarity of a solution made by dissolving 21.2 g of a sodium hydroxide (NaOH) in enough water to make 7.92 L of solution?

Formula for molarity is

Molarity=moles of solvent/solution in liters

In given data

NaOH is 21.2g which is needed to be convert in moles first

As no. of moles=mass in gram/molar mass

Molar mass of NaOH is 39.997g/mol

Putting in formula for mole. we get

No of mole = 21.2g/39.997gper mole

= 0.530mole

Now put these values in molarity equation, we get

Molarity = moles of NaOH / solution in liter

= 0.530/7.92

=0.067M NaOH