Correct statement about FeO at room temperature

Options

A. It is non-stoichiometric and metal deficient
B. It is acidic oxide
C. Its aqueous solution changes to `Fe(OH)_(2)` and then to `Fe_(2)O_(3)`.x `H_(2)O` by atmospheric oxygen
D. It gives red colour with KCNS

Answer

To determine the correct statement about FeO at room temperature, we will analyze the properties and behavior of FeO (iron(II) oxide) systematically.

### Step-by-Step Solution:

**Step 1: Identify the oxidation state of iron in FeO.**
- In FeO, iron (Fe) has an oxidation state of +2, while oxygen (O) has an oxidation state of -2. This gives the compound an overall neutral charge.

**Hint for Step 1:** Remember that the oxidation states of elements in a compound must sum to zero for neutral compounds.

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**Step 2: Analyze the stoichiometry of FeO.**
- FeO is typically represented as FeO, which indicates a 1:1 ratio of Fe to O. However, in some cases, it can exhibit non-stoichiometric behavior, such as in the form Fe₀.₉₅O, which indicates a deficiency in metal (Fe).

**Hint for Step 2:** Non-stoichiometric compounds can have variations in their metal-to-non-metal ratios.

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**Step 3: Determine the nature of FeO (acidic or basic).**
- Since FeO contains iron in the +2 oxidation state, it behaves as a basic oxide. Basic oxides typically react with acids to form salts and water.

**Hint for Step 3:** Basic oxides are usually formed from metals in lower oxidation states.

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**Step 4: Examine the reaction of FeO with water.**
- When FeO reacts with water, it forms iron(II) hydroxide, Fe(OH)₂. This indicates that FeO can indeed react with water to form a hydroxide.

**Hint for Step 4:** Hydroxides of metals are often formed when metal oxides react with water.

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**Step 5: Investigate the reaction of FeO with potassium thiocyanate (KSCN).**
- When Fe²⁺ ions from FeO react with KSCN, they form a red complex, iron(II) thiocyanate, which is Fe(SCN)₂. This indicates a reaction occurs, producing a colored solution.

**Hint for Step 5:** Complex formation can lead to color changes, which are often used as indicators in chemical reactions.

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### Conclusion:
Based on the analysis, the correct statement about FeO at room temperature is that it reacts with water to form Fe(OH)₂, which is consistent with the properties of FeO as a basic oxide.

**Final Answer:** The correct statement about FeO at room temperature is that it forms Fe(OH)₂ in aqueous solution.