The amount of Na ₂ ~S ₂ O ₃ .5 H ₂ O required to completely reduce 100 ~mL of 0.25 ~N iodine solution, is

Step-by-step solution

N ₁ ~V ₁= N ₂ ~V ₂ mili eq. of hypo =0.25 100 mili eq. of hypo =25 eq. of hypo =0.025 mole of hypo =0.025 1 V _ f =1 weight of hypo =0.025 248=6.2 ~g