# Doubt from stoichiometry

In question 5 i am getting option C as answer but answer key says option D why ?
In question 4 i am getting as 2Mn2+ +PbO2 +4H+ so answer should be 2:1:4 but it doesn't matches with any option ?

\displaystyle FeS_2+8H_2O \rightarrow Fe^{+3}+2SO_4^{-2}+16H^+ +15e^-

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For 4 I got
1:3:4

I got 3x=y for first

Sorry for the mistake for 4 I got C
2Mn^{+2}+5PbO_2+4H^+ \rightarrow 5Pb^{+2}+2MnO_4^{-}+2H_2O

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But for first answer is x=2y

Apply law of equivalent concept.
In that question

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Oops I was so dividing instead of multiplying n factor.