Question

Among the following, the correctly matched pair is:

• A. \( \text{electron deficient hydride - SiH}_4 \)
• B. \( \text{saline hydride - CrH} \)
• C. \( \text{electron precise hydride - HF} \)
• D. \( \text{electron rich hydride - NH}_3 \)

Hint:

Electron rich hydrides are those where the central atom has a lone pair of electrons, as seen in \( \text{NH}_3 \).

Answer 1

The Correct Option is D

In this question, we are tasked with identifying the correct pair of hydrides. Let’s analyze each option: 1. Electron deficient hydrides are typically formed by elements that do not have a full octet of electrons, such as \( \text{SiH}_4 \), which does not fit this definition. Hence, this is not the correct answer. 2. Saline hydrides are those formed with alkali and alkaline earth metals, not \( \text{CrH} \), so option (2) is incorrect. 3. Electron precise hydrides are those where the central atom has a complete octet. \( \text{HF} \), however, doesn't qualify as electron precise, hence this pair is incorrect. 4. Electron rich hydrides such as \( \text{NH}_3 \) are correct because nitrogen has a lone pair of electrons that make it electron-rich. Thus, the correct answer is option (4).

Answer 2

Step 1: Understanding Electron Rich Hydrides
Electron rich hydrides are compounds where the central atom has a lone pair of electrons, making the molecule rich in electron density. These hydrides often act as Lewis bases and show properties such as basicity and the ability to donate a lone pair.

Step 2: Analyzing Common Hydrides
- NH₃ (Ammonia) has a lone pair on nitrogen, making it electron rich.
- Other hydrides like PH₃, AsH₃, etc., also have lone pairs but are less basic and less electron rich compared to NH₃ due to poorer overlap and larger atomic size.

Step 3: Correctly Matched Pair
Among the options, "electron rich hydride – NH₃" is correctly matched because ammonia has a lone pair and high electron density around nitrogen.

Step 4: Conclusion
Therefore, the correct matched pair is electron rich hydride – NH₃.