Which of the following statements is correct ?

Options

A. Elements of group 15 from electron deficient hydrides.
B. All elements of group 14 from electron deficient hydrides
C. Electron precise hydrides have tetrahedral geometries
D. Electron rich hydrides can act as Lewis acids.

Explanation

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

### Step 1: Analyze the first statement
**Statement:** Elements of group 15 form electron deficient hydrides.

- **Explanation:** Group 15 elements include nitrogen, phosphorus, arsenic, etc. The hydride of nitrogen is ammonia (NH₃). Nitrogen has 5 valence electrons, and in ammonia, it forms three bonds with hydrogen and retains one lone pair. This indicates that ammonia is electron-rich, not electron-deficient. Therefore, this statement is **incorrect**.

### Step 2: Analyze the second statement
**Statement:** All the elements of group 14 form electron deficient hydrides.

- **Explanation:** Group 14 elements include carbon, silicon, germanium, etc. The hydride of carbon is methane (CH₄). Carbon has 4 valence electrons and forms four bonds with hydrogen, completing its octet without any lone pairs. This means that methane is electron-precise, not electron-deficient. Therefore, this statement is also **incorrect**.

### Step 3: Analyze the third statement
**Statement:** Electron precise hydrides have a tetrahedral structure.

- **Explanation:** As established, methane (CH₄) is an example of an electron-precise hydride. The molecular geometry of methane is tetrahedral due to the four bond pairs and no lone pairs around the central carbon atom. The steric number is 4, which corresponds to sp³ hybridization and a tetrahedral shape. Therefore, this statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement:** Electron rich hydrides can act as Lewis acids.

- **Explanation:** Electron-rich hydrides, such as ammonia (NH₃), possess a lone pair of electrons, which allows them to donate electrons. This characteristic makes them Lewis bases, not Lewis acids. Lewis acids are defined as electron-deficient species that accept electrons. Therefore, this statement is **incorrect**.

### Conclusion
After analyzing all the statements, the only correct statement is the third one: **Electron precise hydrides have a tetrahedral structure.**

### Final Answer
The correct statement is: **3. Electron precise hydrides have a tetrahedral structure.**

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