Three hydrocarbons X, Y and Z are shown below:
`X:CH_(3)CH_(2)CH_(2)CH_(2)CH_(3),Y:CH_(3)-C-=C-CH_(2)CH_(3)`
`Z:CH_(3)CH_(2)-CH=CH-CH_(3)`
Identify the incorrect statements about these three hydrocarbons.
I. X and Y both differ by a `-CH_(2)` unit.
II. X and Z have the same boiling point.
III. All have different general formulae.
IV. Y and Z have different molecular masses.

Options

A. I and II
B. II and III
C. I and IV
D. All the statements are incorrect

Explanation

To solve the problem, we need to analyze the three hydrocarbons (X, Y, and Z) and evaluate the given statements one by one.

### Step 1: Identify the hydrocarbons
- **X**: CH₃CH₂CH₂CH₂CH₃ (This is pentane, an alkane)
- **Y**: CH₃-C≡C-CH₂CH₃ (This is 1-pentyne, an alkyne)
- **Z**: CH₃CH₂-CH=CH-CH₃ (This is 2-pentene, an alkene)

### Step 2: Evaluate the statements
1. **Statement I**: "X and Y both differ by a -CH₂ unit."
- **Analysis**: X (alkane) and Y (alkyne) belong to different families and do not differ by a -CH₂ unit. This statement is **incorrect**.

2. **Statement II**: "X and Z have the same boiling point."
- **Analysis**: X (alkane) and Z (alkene) have different boiling points due to their different structures and types of bonding. This statement is also **incorrect**.

3. **Statement III**: "All have different general formulae."
- **Analysis**:
- General formula for alkanes (X) is CₙH₂ₙ₊₂.
- General formula for alkenes (Z) is CₙH₂ₙ.
- General formula for alkynes (Y) is CₙH₂ₙ₋₂.
- Since they belong to different families, this statement is **correct**.

4. **Statement IV**: "Y and Z have different molecular masses."
- **Analysis**:
- Y has 5 carbon atoms and 8 hydrogen atoms (C₅H₈).
- Z has 5 carbon atoms and 10 hydrogen atoms (C₅H₁₀).
- Since the number of hydrogen atoms is different, their molecular masses are also different. This statement is **correct**.

### Conclusion
The incorrect statements are:
- Statement I: X and Y both differ by a -CH₂ unit.
- Statement II: X and Z have the same boiling point.

### Final Answer
The incorrect statements about these three hydrocarbons are I and II.

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