Which of the following statements is correct?

Options

A. Metallic hydrides are deficient of hydrogen
B. Metallic hydrides conduct heat and electricity
C. Ioniuc hyrdrieds do not conduct electricity in solid state
D. ionic hydrides are very good conductors of electricity is solid state.

Explanation

To determine which statements are correct regarding metallic and ionic hydrides, we will evaluate each statement one by one.

### Step 1: Evaluate the first statement
**Statement 1:** Metallic hydrides are deficient of hydrogen.

- **Analysis:** Metallic hydrides are known to be non-stoichiometric, meaning they do not have a fixed ratio of metal to hydrogen. This non-stoichiometry indicates that they can have varying amounts of hydrogen, often leading to a deficiency of hydrogen in their structure.

**Conclusion:** This statement is correct.

### Step 2: Evaluate the second statement
**Statement 2:** Metallic hydrides conduct heat and electricity.

- **Analysis:** Metallic hydrides, like metals, have free electrons that allow them to conduct heat and electricity effectively. This property is characteristic of metallic bonding.

**Conclusion:** This statement is also correct.

### Step 3: Evaluate the third statement
**Statement 3:** Ionic hydrides do not conduct electricity in solid state.

- **Analysis:** Ionic hydrides consist of ionic bonds, and in the solid state, they do not have free-moving ions. Without free ions, there is no conduction of electricity.

**Conclusion:** This statement is correct.

### Step 4: Evaluate the fourth statement
**Statement 4:** Ionic hydrides are very good conductors of electricity in solid state.

- **Analysis:** This statement is incorrect because, as established, ionic hydrides do not conduct electricity in the solid state due to the absence of free ions. They can conduct electricity only when they are in aqueous solution or molten state, where ions are free to move.

**Conclusion:** This statement is incorrect.

### Final Conclusion
Based on the evaluations:
- **Correct Statements:** 1, 2, and 3.
- **Incorrect Statement:** 4.

### Answer:
The correct statements are 1, 2, and 3.

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