The compound that gets oxidised even on exposure to atmosphere is:

Options

A. `Co_(2)(SO_(4))_(3)`
B. `NiSO_(4)`
C. `KMnO_(4)`
D. `FeSO_(4)`

Explanation

To determine which compound gets oxidized even on exposure to the atmosphere, we will analyze each of the given options step by step.

### Step 1: Analyze Cobalt Sulfate (Co2SO4)
- Cobalt sulfate is not very sensitive to moisture at room temperature.
- It does not react with water, which means it will not undergo oxidation or reduction in the presence of moisture.
- **Conclusion**: Cobalt sulfate does not get oxidized when exposed to the atmosphere.

**Hint**: Consider the reactivity of cobalt compounds with water and oxygen at room temperature.

### Step 2: Analyze Nickel Sulfate (NiSO4)
- Nickel is also resistant to atmospheric corrosion and does not react readily with moisture at room temperature.
- Therefore, nickel sulfate will not undergo oxidation in the presence of moisture or atmospheric oxygen.
- **Conclusion**: Nickel sulfate does not get oxidized when exposed to the atmosphere.

**Hint**: Look into the corrosion resistance of nickel and its compounds.

### Step 3: Analyze Potassium Permanganate (KMnO4)
- KMnO4 is a strong oxidizing agent.
- In its maximum oxidation state (+7 for manganese), it tends to reduce itself while oxidizing other substances.
- Thus, it does not get oxidized further when exposed to the atmosphere.
- **Conclusion**: KMnO4 does not get oxidized; instead, it acts as an oxidizer.

**Hint**: Recall the oxidation states and the behavior of strong oxidizing agents.

### Step 4: Analyze Iron(II) Sulfate (FeSO4)
- FeSO4 is known to oxidize in the presence of moisture and oxygen from the atmosphere.
- The reaction can be represented as:
\[ 4FeSO_4 + 2H_2O + O_2 \rightarrow 4Fe(OH)SO_4 \]
- This indicates that FeSO4 readily undergoes oxidation when exposed to moisture and atmospheric oxygen.
- **Conclusion**: FeSO4 is the compound that gets oxidized even on exposure to the atmosphere.

**Hint**: Consider the common reactions of iron compounds with moisture and oxygen.

### Final Conclusion
The compound that gets oxidized even on exposure to the atmosphere is **FeSO4** (Iron(II) sulfate).