Calculate the mass in gram of binormal solution in NAOH

80 grams

Explanation:

Normality is one of the units of concentration and it is derived by dividing the gram or mole equivalent of the solute in a solution by the volume (in liters) of the solution.  

The equivalent weight of NaOH is derived by dividing the molecular weight of the compound by 1. Hence, the equivalent weight of NaOH in 1 normal solution is 40/1 = 40 g.

If 1 normal NaOH solution contains 40 g of NaOH in 1 liter of the solution, then a binormal (2 normal) solution of NaOH would contain;

   2 x 40 = 80 g of NaOH.

c) should be the answer.