MCQ
Iron becomes passive by ..................... due to formation of .....................
- Adil. $HCl, Fe_2O_3$
- ✓$80\%$ conc. $HNO_3, Fe_3O_4$
- Cconc. $H_2SO_4, Fe_3O_4$
- Dconc. $HCl, Fe_3O_4$
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$Pt$ $\mid H _{2}$ $(g,1 \,bar)$ $\left| H ^{+}( aq ) \| Cu ^{2+}( aq )\right| Cu ( s )$
is $0.31\, V$. The $pH$ of the acidic solution is found to be $3 ,$ whereas the concentration of $Cu ^{2+}$ is $10^{- x } \,M$. The value of $x$ is $.....$
(Given: $E _{ Cu ^{2+} / Cu }^{\ominus}=0.34 \,V$ and $\frac{2.303 RT }{ F }=0.06\, V$ )


