Question

The oxidation number of arsenic trisulphide $\left({\text{As}}_{\text{2}}{\text{S}}_{\text{3}}\right)$ is ______.

• A. $+1$
• B. $+2$
• C. $+3$
• D. $-3$

Answer 1

The correct option is C

$+3$

The explanation for the correct option

(C)$+3$

Oxidation number

• "Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."

The oxidation number of arsenic trisulphide $\left({\text{As}}_{\text{2}}{\text{S}}_{\text{3}}\right)$.

• Consider the oxidation number of $\mathrm{As}$ is $x$.
• The oxidation number of sulfur is $-2$.

$$\begin{gathered} \mathrm{x}\times 2+\left(-2\times 3\right)=0 \\ \mathrm{x}=+3 \end{gathered}$$

The oxidation number of arsenic trisulphide $\left({\text{As}}_{\text{2}}{\text{S}}_{\text{3}}\right)$ is $+3$.

The explanation for the incorrect option

The oxidation number of arsenic trisulphide $\left({\text{As}}_{\text{2}}{\text{S}}_{\text{3}}\right)$ is $+3$. Hence, options (A), (B), and (D) are incorrect.

Hence, option (C) is correct. The oxidation number of arsenic trisulphide $\left({\text{As}}_{\text{2}}{\text{S}}_{\text{3}}\right)$ is $+3$.