B is the correct answer
3Fe2+ + NO3 - + 4H+ → 3Fe3+ + NO + 2H2O
let vol be v. so number of moles nitirc acid is 6v.
3 moles fe require 1 mole nitirc
so 8/56 moles require 1/3 * 8/56 =6v
so v=7.93 ml
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