Question

Consider the reactions shown below :

Which of the following statements is false?
[Atomic mass of zinc $=65.4$]

• A. Silver chromate has the formula $A{g}_{2}Cr{O}_4$.
• B. The minimum mass of zinc required to reduce $0.100mole$ of $C{r}^{3+}$ to $C{r}^{2+}$ is $6.54g$
• C. The conversion of $Cr{O}_4^{2-}$ into $C{r}_2{O}_7{}^{2-}$ is not a redox reaction.
• D. The equation, $C{r}_2{O}_7^{2-}+14H^{+}+6F{e}^{2+}\to 6F{e}^{3+}+2C{r}^{3+}+7H_{2}O$ correctly describes the reduction of $C{r}_2{O}_7^{2-}$ by acidified $FeS{O}_4$

Answer 1

Answer: (B)

(a) Formula of silver chromate will be $A{g}_{2}Cr{O}_4$

(b) Minimum mass of zinc required for reduction of 0.1 mole of $C{r}^{3+}\text{ to }C{r}^{2+}$

$=\frac{0.1}{2}\text{ moles of }Zn=\frac{6.54}{2}g=3.27g$

(c) $Cr{O}_4^{2-}\rightleftharpoons C{r}_2{O}_7^{2-}$

in both ions chromium is in $+6$ state.

(d) Given reaction is correct.