Question

Assertion :The oxidation state of Cr in $A{l}_2(C{r}_2{O}_7{)}_3$ is +3 Reason: As a neutral compound, the sum of the oxidation numbers of all the atoms must equal zero

• A. Both assertion and reason are correct and reason is the correct explanation for assertion
• B. Both assertion and reason are correct but reason is not the correct explanation for assertion
• C. Assertion is correct but reason is incorrect
• D. Both assertion and reason are incorrect

Answer 1

The correct option is A Both assertion and reason are correct and reason is the correct explanation for assertion

Oxidation state of $Cr$ in $A{l}_2(C{r}_2{O}_7{)}_3$ is $+3$

Therefore, $(2\times 3)+(6\times Cr)+(21\times -2)=0$

$\Rightarrow +6+\left(6x\right)+(-42)=0$

$\Rightarrow 6x-36=0$

$\Rightarrow 6x=36$

$\Rightarrow x=6$.

Charge on Chromium ion is $+6$.

Also, in a neutral compound, the sum of the oxidation numbers of all atoms must be equal to zero.