Which of the following statement is correct here

Options

A. `AgBr` can show both Schottky and Frenkel defects
B. `ZnO` on heating shows metal excess defects
C. `MnO_2` is ferromagnetic substance
D. Both A and B are correct

Answer

To solve the question, we need to evaluate each of the given statements regarding their correctness. Let's analyze them step by step.

### Step 1: Analyze Statement 1
**Statement 1:** Silver bromide can show both Schottky and Frenkel defects.

- **Schottky Defect:** This defect occurs when both cations and anions are missing from their lattice positions.
- **Frenkel Defect:** This defect occurs when some cations leave their normal lattice positions and occupy interstitial positions.

**Analysis:** Silver bromide (AgBr) has a coordination number of 6, which is medium. The size difference between silver ions (Ag⁺) and bromide ions (Br⁻) is significant, allowing for both types of defects to occur. Therefore, this statement is **correct**.

### Step 2: Analyze Statement 2
**Statement 2:** Zinc oxide on heating shows metal excess defect.

- **Metal Excess Defect:** This defect occurs when there is an excess of metal ions in the lattice due to the loss of non-metal ions (like oxygen).

**Analysis:** When zinc oxide (ZnO) is heated, it decomposes and releases oxygen, resulting in an excess of zinc ions in the lattice. This leads to the formation of interstitial zinc ions and electrons to maintain charge neutrality. Therefore, this statement is also **correct**.

### Step 3: Analyze Statement 3
**Statement 3:** MnO₂ is a ferromagnetic substance.

- **Ferromagnetic Substance:** This is a material that has a permanent magnetic moment due to the alignment of magnetic domains.

**Analysis:** Manganese dioxide (MnO₂) is actually an anti-ferromagnetic substance, meaning that its magnetic moments cancel each other out due to opposite orientations. Therefore, this statement is **incorrect**.

### Step 4: Analyze Statement 4
**Statement 4:** This statement combines the first two statements.

**Analysis:** Since both Statement 1 and Statement 2 are correct, and Statement 3 is incorrect, Statement 4, which claims that both Statement 1 and Statement 2 are correct, is also **correct**.

### Conclusion
The correct statements are:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect
- Statement 4: Correct (as it combines the correct statements)

Thus, the correct answer is that both Statement 1 and Statement 2 are correct.

### Final Answer
The correct statements are:
- Statement 1 and Statement 2 are correct.
- Therefore, the answer is Statement 4.

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