Ammoniacal solution of `MgSO_4` in presence of `NH_4Cl` is heated with `Na_2HPO_4` , a white precipitate is formed of

Options

A. `Mg(NH_4)PO_4`
B. `Mg_3(PO_3)_2`
C. `MgSO_4. MgCl_2`
D. `MgSO_4. MgPO_4`

Explanation

To solve the question regarding the formation of a white precipitate when an ammoniacal solution of `MgSO4` in the presence of `NH4Cl` is heated with `Na2HPO4`, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reactants**:
- We have an ammoniacal solution of magnesium sulfate (`MgSO4`) and ammonium chloride (`NH4Cl`).
- We are adding disodium hydrogen phosphate (`Na2HPO4`) to this solution.

2. **Identify the Ions Present**:
- From `MgSO4`, we have `Mg^2+` and `SO4^2-`.
- From `NH4Cl`, we have `NH4^+` and `Cl^-`.
- From `Na2HPO4`, we have `Na^+` and `HPO4^2-`.

3. **Consider the Reaction**:
- In the presence of ammonia (`NH3`), magnesium ions can form a complex with ammonium phosphate.
- The relevant reaction can be represented as:
\[ Mg^{2+} + NH4^+ + HPO4^{2-} \rightarrow MgNH4PO4 \]

4. **Formation of Precipitate**:
- The compound formed, `MgNH4PO4`, is a white precipitate. This is because magnesium ammonium phosphate is insoluble in water.

5. **Evaluate the Options**:
- The options provided are:
1. `MgNH4PO4`
2. `Mg3(PO3)2`
3. `MgSO4.MgCl2`
4. `MgSO4.MgPO4`
- From our reaction, we can see that the correct precipitate formed is `MgNH4PO4`, which corresponds to option 1.

### Final Answer:
The white precipitate formed is **`MgNH4PO4`**.

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