The correct order for melting point and boiling point of IV group hydrides respectively
I) `CH_(4) lt SiH_(4) lt GeH_(4) lt SnH_(4)`
II) `CH_(4) gt SiH_(4) lt GeH_(4) lt SnH_(4)`
III) `SnH_(4) lt GeH_(4) lt SiH_(4) lt CH_(4)`
IV) `CH_(4) lt SiH_(4) gt GeH_(4) gt SnH_(4)`

Options

A. II,I
B. I,II
C. III, IV
D. IV, III

Answer

To determine the correct order for the melting point and boiling point of Group IV hydrides (CH₄, SiH₄, GeH₄, SnH₄), we need to analyze the factors affecting these properties.

### Step-by-Step Solution:

1. **Identify the Hydrides**: The hydrides we are considering are:
- Methane (CH₄)
- Silane (SiH₄)
- Germanium hydride (GeH₄)
- Stannane (SnH₄)

2. **Understand the Trends**:
- As we move down the group from carbon to lead, the molecular mass of the hydrides increases.
- The boiling and melting points are influenced by the strength of intermolecular forces, which are primarily Van der Waals forces in these hydrides.

3. **Evaluate Molecular Mass**:
- CH₄ has the lowest molecular mass.
- SiH₄ has a higher molecular mass than CH₄.
- GeH₄ has a higher molecular mass than SiH₄.
- SnH₄ has the highest molecular mass among these hydrides.

4. **Assess Intermolecular Forces**:
- Van der Waals forces increase with increasing molecular mass.
- Therefore, SnH₄, having the highest molecular mass, will have the strongest intermolecular forces, leading to the highest boiling and melting points.

5. **Determine the Order**:
- For boiling points: The order will be SnH₄ > GeH₄ > SiH₄ > CH₄.
- For melting points: The order will be similar, but CH₄ will have the lowest melting point due to its tetrahedral structure allowing it to be more easily melted.

6. **Check the Options**:
- I) `CH₄ < SiH₄ < GeH₄ < SnH₄` (This is incorrect for boiling points)
- II) `CH₄ > SiH₄ < GeH₄ < SnH₄` (This is incorrect for both)
- III) `SnH₄ < GeH₄ < SiH₄ < CH₄` (This is incorrect)
- IV) `CH₄ < SiH₄ > GeH₄ > SnH₄` (This is incorrect)

7. **Conclusion**:
- The correct order for boiling points is SnH₄ > GeH₄ > SiH₄ > CH₄.
- The correct order for melting points is also SnH₄ > GeH₄ > SiH₄ > CH₄, but CH₄ has the lowest melting point.

### Final Answer:
None of the provided options correctly represent the order for both melting and boiling points of Group IV hydrides.