Identify the incorrect formulae among the following : (A) `CaO_(2)` (B) `Na_(2)O`
(C ) `Mg_(3)S_(2)` (D) `Mg_(2)O`

Options

A. A,B,D
B. A,C,D
C. C,D,E
D. B,C,D

Explanation

To identify the incorrect formulae among the given options, we will analyze each formula based on the known oxidation states of the elements involved.

### Step-by-Step Solution:

1. **Analyze Option (A): `CaO2`**
- Calcium (Ca) typically has an oxidation state of +2.
- Oxygen (O) typically has an oxidation state of -2.
- For `CaO`, the formula would be balanced as Ca^2+ and O^2-.
- However, `CaO2` suggests that there are two oxygen atoms for one calcium atom, which would imply an oxidation state of -1 for oxygen (not typical).
- Therefore, `CaO2` is incorrect.

2. **Analyze Option (B): `Na2O`**
- Sodium (Na) typically has an oxidation state of +1.
- Oxygen (O) typically has an oxidation state of -2.
- For `Na2O`, we have 2 Na^+ (total +2) and 1 O^2- (total -2), which balances correctly.
- Therefore, `Na2O` is correct.

3. **Analyze Option (C): `Mg3S2`**
- Magnesium (Mg) typically has an oxidation state of +2.
- Sulfur (S) typically has an oxidation state of -2.
- For `Mg3S2`, we have 3 Mg^2+ (total +6) and 2 S^2- (total -4), which does not balance correctly.
- The correct formula should be `MgS` (one magnesium for one sulfur) or `Mg2S` (two magnesium for one sulfur).
- Therefore, `Mg3S2` is incorrect.

4. **Analyze Option (D): `Mg2O`**
- Magnesium (Mg) has an oxidation state of +2.
- Oxygen (O) has an oxidation state of -2.
- For `Mg2O`, we have 2 Mg^2+ (total +4) and 1 O^2- (total -2), which does not balance correctly.
- The correct formula should be `MgO` (one magnesium for one oxygen).
- Therefore, `Mg2O` is incorrect.

### Conclusion:
The incorrect formulae among the options provided are:
- (A) `CaO2`
- (C) `Mg3S2`
- (D) `Mg2O`

### Final Answer:
The incorrect formulae are (A), (C), and (D).

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