Which of the following statements regarding hydrides is not correct ?

Options

A. Ionic hydrides are crystalline, non - volatile and non-conducting in solid state.
B. Electron - deficient hydrides act as Lewis acids or electron acceptors.
C. Elements of group - 13 form electron - deficient hydrides.
D. Elements of group 15 - 17 form electron - precise hydrides.

Explanation

To determine which statement regarding hydrides is not correct, we need to analyze each statement provided in the question.

**Step 1: Analyze Statement 1**
- Statement: "Ionic hydrides are crystalline, non-volatile, and non-conducting in solid state."
- Explanation: Ionic hydrides, such as sodium hydride (NaH) and potassium hydride (KH), are indeed crystalline in nature. They are non-volatile because they do not easily evaporate and are also non-conducting in their solid state due to the lack of free-moving ions.
- Conclusion: This statement is **correct**.

**Step 2: Analyze Statement 2**
- Statement: "Electron deficient hydrides act as Lewis acids or electron acceptors."
- Explanation: Electron deficient hydrides, such as boron hydride (BH3), do act as Lewis acids because they can accept electrons due to having fewer than eight electrons in their valence shell.
- Conclusion: This statement is **correct**.

**Step 3: Analyze Statement 3**
- Statement: "Elements of group 13 form electron deficient hydrides."
- Explanation: Group 13 elements, such as boron and aluminum, do indeed form electron deficient hydrides. For example, diborane (B2H6) is an electron deficient hydride.
- Conclusion: This statement is **correct**.

**Step 4: Analyze Statement 4**
- Statement: "Elements of group 15 to 17 form electron precise hydrides."
- Explanation: This statement is misleading. Elements of group 15 (like nitrogen), 16 (like oxygen), and 17 (like fluorine) typically form electron-rich hydrides. For instance, ammonia (NH3) is an electron-rich hydride from group 15.
- Conclusion: This statement is **not correct**.

**Final Answer:**
The statement that is not correct is **Statement 4**: "Elements of group 15 to 17 form electron precise hydrides."

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