Which of the following statement is false `:`

Options

A. The milk of magnesia used as antacid is chemically `MgO+MgCl_(2)`
B. Stability of alkali metal peroxides increases with increase in atomic number
C. Hydration energy of `AgF` is higher than its lattice energy
D. Anhydrous `MgCl_(2)` cannot be prepared by direct heating of `MgCl_(2).6H_(2)O`

Explanation

To determine which of the statements is false, we will analyze each statement provided in the question step by step.

### Step 1: Analyze Statement A
**Statement A:** The milk of magnesia used as an antacid is chemically MgO plus MgCl2.

- **Analysis:** Milk of magnesia is commonly known as magnesium hydroxide, which is represented as Mg(OH)₂. The statement claims it is a combination of MgO and MgCl2, which is incorrect. Therefore, this statement is false.

### Step 2: Analyze Statement B
**Statement B:** The stability of alkali metal peroxides increases with an increase in atomic number.

- **Analysis:** As we move down the group in the periodic table, the size of the alkali metals increases, leading to greater stability of their peroxides. This statement is true.

### Step 3: Analyze Statement C
**Statement C:** The hydration energy of AgF is higher than its lattice energy.

- **Analysis:** Hydration energy refers to the energy released when ions are surrounded by water molecules. For AgF, the small size of the fluoride ion (F⁻) leads to a high hydration energy compared to its lattice energy. Thus, this statement is true.

### Step 4: Analyze Statement D
**Statement D:** Anhydrous MgCl2 cannot be prepared by direct heating of MgCl2·6H2O.

- **Analysis:** When MgCl2·6H2O is heated, it loses water molecules to form MgCl2, but this MgCl2 is not anhydrous; it retains some water of crystallization. Therefore, this statement is also false.

### Conclusion
Based on the analysis, the false statements are:
- **Statement A:** False (Milk of magnesia is Mg(OH)₂, not MgO + MgCl2)
- **Statement D:** False (Heating MgCl2·6H2O does not yield anhydrous MgCl2)

Since the question asks for which statement is false, the correct answer is **Statement A**.

### Final Answer
The false statement is: **A. The milk of magnesia used as antacid is chemically MgO plus MgCl2.**

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