The percentage (by weight) of sodium hydroxide in a 1.25 molal NaOH solution is

The 1.25 molal solution of NaOH means that the 1.25 moles of NaOH dissolve in 1000 g of water. Therefore, the weight of NaOH is calculated as, weight of NaOH = 1.25 40 50g x Weight of solution is equal to, weight of solution = 1000 + 50 = 1050 g Therefore, 0 0 the weight of the solution is, 0 0 0 0 0 0 0 0 wt.of solute (by weight) of NaOH = 100 wt.of solution 50 (by weight) of NaOH = 100 1050 (by weight) of NaOH 4.76 x >> x Therefore, the percentage weight of NaOH is 0 0 4.76 . Thus, (a) is the correct option.