When 80 g of sodium hydroxide, naoh, are dissolved in enough water to make 500 ml of solution, the molarity of the solution is — a 1 m b 2 m c 4 m d 8 m?

Answer is: molarity of sodium hydroxide solution is c. 4 M.
m(NaOH) = 80.0 g.
n(NaOH) = m(NaOH) ÷ M(NaOH).
n(NaOH) = 80 g ÷ 40 g/mol.
n(NaOH) = 2 mol.
V(NaOH) = 500 mL ÷ 1000 mL/L = 0.5 L.
c(NaOH) = n(NaOH) ÷ V(NaOH).
c(NaOH) = 2 mol ÷ 0.5 L.
c(NaOH) = 4 mol/L.

n - amount of substance.