Question

Among the following, the molecular hydride is:

• A. BeH\(_2\)
• B. B\(_2\)H\(_6\)
• C. NaH
• D. CrH

Hint:

Molecular hydrides are covalent, often volatile and involve p-block elements like boron.

Answer 1

The Correct Option is B

Hydrides are classified as:
- Ionic hydrides → with metals (e.g., NaH)
- Covalent/molecular hydrides → with p-block elements (e.g., B\(_2\)H\(_6\))
- Metallic hydrides → transition elements (e.g., CrH)
Out of the given:
- B\(_2\)H\(_6\) (Diborane) is a typical molecular hydride
- BeH\(_2\) is polymeric
- NaH is ionic
- CrH is metallic

Answer 2

Among the following, the molecular hydride is:

Step 1: Understand what molecular hydrides are:
Hydrides are compounds formed by hydrogen with other elements. They can be classified into three types:
- Ionic (saline) hydrides: formed with highly electropositive metals like alkali and alkaline earth metals.
- Covalent (molecular) hydrides: formed with non-metals and metalloids, where hydrogen is covalently bonded.
- Metallic hydrides: formed with transition metals, where hydrogen atoms occupy interstitial sites in the metal lattice.

Step 2: Identify B₂H₆ (diborane):
Diborane (B₂H₆) is a well-known covalent compound and is classified as a molecular hydride. It has a unique structure involving 2-center–2-electron and 3-center–2-electron bonds. The hydrogen atoms in B₂H₆ are covalently bonded, making it a typical example of a molecular (covalent) hydride.

Step 3: Conclusion:
Among various options typically given in such questions, B₂H₆ is the compound that clearly fits the definition of a molecular hydride.

Final Answer:
\[ \boxed{\text{B}_2\text{H}_6} \]