Question

question 2. what is the correct formula for the ionic compound formed between the chromium(iii) ion and the sulfide ion?
○ crs
○ cr₂s₃
○ cr₃s
○ crs₂

Explanation:

Step1: Identify ion charges

Chromium(III) ion: $\text{Cr}^{3+}$ (charge +3). Sulfide ion: $\text{S}^{2-}$ (charge -2).

Step2: Balance charges

To balance positive and negative charges, find the least common multiple of 3 and 2, which is 6. Number of $\text{Cr}^{3+}$ ions: $\frac{6}{3} = 2$. Number of $\text{S}^{2-}$ ions: $\frac{6}{2} = 3$.

Step3: Write formula

Combine ions: 2 $\text{Cr}^{3+}$ and 3 $\text{S}^{2-}$ give $\text{Cr}_2\text{S}_3$.

Answer:

$\text{Cr}_2\text{S}_3$ (corresponding to the option $\boldsymbol{\text{Cr}_2\text{S}_3}$)