Q20 / 180 · COMEDK 2024 (Morning Shift) · Chemistry
An inorganic salt comprises of atoms of elements $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$. If the oxidation numbers of A, B and $\mathrm{C}$ are $+3,+6$ and $-$2 respectively, what is the possible formula of the compound?
- A$\mathrm{A}_3 \mathrm{B}_6 \mathrm{C}_2$
- Correct answerB$\mathrm{A}_2\left(\mathrm{BC}_4\right)_3$
- C$\mathrm{A}_3\left(\mathrm{BC}_3\right)_4$
- D$\mathrm{A}_3(\mathrm{BC})_2$
Solution
Let the formula of the compound be $\mathrm{A}_x(\mathrm{B}_y\mathrm{C}_z)_w$. The sum of oxidation states in a neutral compound must be zero.
Given oxidation numbers: $\mathrm{A} = +3$, $\mathrm{B} = +6$, $\mathrm{C} = -2$.
Consider the option $\mathrm{A}_2(\mathrm{BC}_4)_3$.
The total charge is calculated as: $2 \times (+3) + 3 \times [1 \times (+6) + 4 \times (-2)]$.
$= 6 + 3 \times [6 - 8] = 6 + 3 \times (-2) = 6 - 6 = 0$.
Since the sum of oxidation states is zero, the formula $\mathrm{A}_2(\mathrm{BC}_4)_3$ is electrically neutral and represents a possible inorganic salt.
Answer: $\mathrm{A}_2\left(\mathrm{BC}_4\right)_3$
Given oxidation numbers: $\mathrm{A} = +3$, $\mathrm{B} = +6$, $\mathrm{C} = -2$.
Consider the option $\mathrm{A}_2(\mathrm{BC}_4)_3$.
The total charge is calculated as: $2 \times (+3) + 3 \times [1 \times (+6) + 4 \times (-2)]$.
$= 6 + 3 \times [6 - 8] = 6 + 3 \times (-2) = 6 - 6 = 0$.
Since the sum of oxidation states is zero, the formula $\mathrm{A}_2(\mathrm{BC}_4)_3$ is electrically neutral and represents a possible inorganic salt.
Answer: $\mathrm{A}_2\left(\mathrm{BC}_4\right)_3$
Hence, the correct answer is option: 'B'.