1. Find the oxidation-state distribution in $\mathrm{Fe_{0.93}O}$

Let in $1$ mole of $\mathrm{Fe_{0.93}O}$:

• moles of $\mathrm{Fe^{2+}} = x$
• moles of $\mathrm{Fe^{3+}} = y$

Since total Fe per formula unit is $0.93$, $x+y=0.93$

For electrical neutrality with one $\mathrm{O^{2-}}$: $2x+3y=2$

Solving: From $x=0.93-y$, $2(0.93-y)+3y=2$ $1.86-2y+3y=2$ $y=0.14$ Hence, $x=0.93-0.14=0.79$

So in $1$ mole of $\mathrm{Fe_{0.93}O}$:

• $\mathrm{Fe^{2+}} = 0.79$ mol
• $\mathrm{Fe^{3+}} = 0.14$ mol

2. Check statement B

Statement B says the number of moles of $\mathrm{Fe^{2+}}$ and $\mathrm{Fe^{3+}}$ in $1$ mole of $\mathrm{Fe_{0.93}O}$ are $0.79$ and $0.14$ respectively.

This matches our calculation.

✅ B is correct

3. Check statement D

Percentage composition among total Fe ions: $\%\,\mathrm{Fe^{2+}}=\frac{0.79}{0.93}\times 100\approx 84.95\%\approx 85\%$ $\%\,\mathrm{Fe^{3+}}=\frac{0.14}{0.93}\times 100\approx 15.05\%\approx 15\%$

So statement D is correct.

✅ D is correct

4. Check statement C

$\mathrm{Fe_{0.93}O}$ has fewer Fe atoms than stoichiometric $\mathrm{FeO}$, so it is metal deficient.

Also, wustite-type structure is based on a cubic close packed arrangement of $\mathrm{O^{2-}}$ ions with Fe occupying octahedral holes, and some Fe vacancies are present.

✅ C is correct

5. Check statement A (equivalent weight)

Equivalent weight in this oxidation process is: $\text{Equivalent weight} = \frac{\text{molar mass}}{n\text{-factor}}$

Here $\mathrm{Fe_{0.93}O}$ is oxidized to $\mathrm{Fe_2O_3}$, where all iron becomes $\mathrm{Fe^{3+}}$.

Initially in $1$ mole of $\mathrm{Fe_{0.93}O}$:

• $0.79$ mol of $\mathrm{Fe^{2+}}$ are oxidized to $\mathrm{Fe^{3+}}$
• each such Fe loses $1$ electron

So total electrons lost per mole of $\mathrm{Fe_{0.93}O}$: $n = 0.79$

Therefore, $\text{Equivalent weight} = \frac{\text{molar mass of }\mathrm{Fe_{0.93}O}}{0.79}$

✅ A is correct

6. Total number of correct statements

Correct statements are: $A,\ B,\ C,\ D$

Hence, the number of correct statements is $\boxed{4}$

7. Comparison with stored answer

Stored correct answer: $4$

Our derived answer: $4$

They match.