20mL of 0 . 02 MK _ 2 Cr _ 2 O _ 7 solution is used for the...

Equivalents of ${K}_{2}{Cr}_{2}{O}_{7} =$ Equivalents of ${Fe}^{2 +}$

$⇒$(Molarity $\times$ volume $\times$ $n . f$)$of {K}_{2}{Cr}_{2}{O}_{7} =$ (molarity $\times$ volume $\times$ $n . f$)$of {Fe}^{2 +}$

$n . f = n - factor ( valencefactor )$

$⇒ 0 . 02 \times 20 \times 6 = M \times 10 \times 1$

$⇒ M = 0 . 24$

$⇒$ Molarity $= 24 \times {10}^{- 2}$