QJEEM21Ch8ff7: JEE Main 2021 Chemistry - Class 11 JEEM21Ch8ff7 Solution: In basic medium oxidises to form and itself changes into . The…

Question

Verified Solution • 2025–26 Session moderate

In basic medium

Cr{O_4}^{2 - }

oxidises

{S_2}{O_3}^{2 - }

to form

S{O_4}^{2 - }

and itself changes into

Cr{(OH)_4}^ -

. The volume of 0.154 M

Cr{O_4}^{2 - }

required to react with 40 mL of 0.25 M

{S_2}{O_3}^{2 - }

is __________ mL. (Rounded off to the nearest integer)

Accepted Answer

17 H_{2} O + 8 C r O_{4} + 3 S_{2} O_{3} \overset{}{⟶} 6 S O_{4} + 8 C r {(O H)_{4}}^{-} + 2 O H^{-}

Applying mole-mole analysis

{{0.154 \times v} \over 8} = {{40 \times 0.25} \over 3}

v = 173 mL

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