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 peroxide incease with increase in atomic numbers
C. Hydration energy of AgF is higher than its lattice energy
D. Anhydrous `MgCl_(2)` cannot be prepared by direct heating of `MaCl_(2)*6H_(2)O`

Explanation

To determine which statement is false among the given options, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** Milk of magnesia used as antacid is chemically MgO + MgCl2.

- **Analysis:** This statement is incorrect. Milk of magnesia is actually a suspension of magnesium hydroxide, which can be represented as Mg(OH)₂. It is formed from the reaction of MgO with water (H₂O), not with MgCl₂. Therefore, the correct representation would be MgO + H₂O → Mg(OH)₂.

**Conclusion:** The first statement is false.

### Step 2: Analyze the Second Statement
**Statement:** Stability of alkali metal peroxide increases with increase in atomic number.

- **Analysis:** This statement is true. As we move down the group in the periodic table, the stability of alkali metal peroxides (like Na₂O₂, K₂O₂, etc.) increases due to the larger atomic size and lower charge density of the metal cations, which leads to greater stability of the peroxide ion.

**Conclusion:** The second statement is true.

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

- **Analysis:** This statement is true. The hydration energy of AgF (silver fluoride) is indeed higher than its lattice energy. The hydration energy is the energy released when ions are surrounded by water molecules, and in the case of AgF, the hydration energy surpasses the energy required to break the lattice structure.

**Conclusion:** The third statement is true.

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

- **Analysis:** This statement is true. When MgCl₂·6H₂O is heated, it loses water molecules but does not yield anhydrous MgCl₂ directly. Instead, it forms MgCl₂·nH₂O (with n being less than 6) before it can be converted to anhydrous MgCl₂. Thus, direct heating does not yield anhydrous MgCl₂.

**Conclusion:** The fourth statement is true.

### Final Conclusion
After analyzing all the statements, we find that the first statement is false. Therefore, the answer to the question is:

**Answer:** The false statement is: "Milk of magnesia used as antacid is chemically MgO + MgCl2."

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