Which of the statement is correct ?
I. Melting point of alkane increases with increase of C atoms and with increase in branching.
II. Boiling point of alkane increases with increase of C atoms but with decrease in branching.
III. Cycloalkanes have lower boiling point than normal alkane with same numer of C atoms.
IV. Alkenes have lower boiling point than same number of C atoms in alkanes.

Options

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

Explanation

To determine which statements are correct regarding alkanes, cycloalkanes, and alkenes, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyzing Statement I:**
- **Statement:** Melting point of alkane increases with increase of C atoms and with increase in branching.
- **Analysis:**
- The melting point of alkanes does indeed increase with the number of carbon atoms because larger molecules have more surface area, which leads to stronger van der Waals forces.
- Additionally, as branching increases, the molecules become more compact, which also enhances the strength of van der Waals forces, leading to a higher melting point.
- **Conclusion:** This statement is **correct**.

2. **Analyzing Statement II:**
- **Statement:** Boiling point of alkane increases with increase of C atoms but with decrease in branching.
- **Analysis:**
- The boiling point of alkanes increases with the number of carbon atoms due to increased surface area and stronger van der Waals forces.
- However, as branching increases, the surface area decreases, leading to weaker van der Waals forces and a lower boiling point. Thus, less branching correlates with a higher boiling point.
- **Conclusion:** This statement is **correct**.

3. **Analyzing Statement III:**
- **Statement:** Cycloalkanes have lower boiling point than normal alkanes with the same number of C atoms.
- **Analysis:**
- Cycloalkanes typically have a larger surface area compared to their straight-chain counterparts, which leads to stronger van der Waals forces and thus a higher boiling point.
- **Conclusion:** This statement is **incorrect**.

4. **Analyzing Statement IV:**
- **Statement:** Alkenes have lower boiling point than the same number of carbon atoms in alkanes.
- **Analysis:**
- Alkenes generally have higher boiling points than alkanes with the same number of carbon atoms due to the presence of a double bond, which introduces additional polarity and stronger intermolecular forces.
- **Conclusion:** This statement is **incorrect**.

### Final Conclusion:
- The correct statements are **I and II**.