1-butene cannot show geometrical isomerism.

Answer

To determine whether 1-butene can show geometrical isomerism, we need to analyze its structure and the conditions required for geometrical isomerism to occur.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
- Geometrical isomerism (also known as cis-trans isomerism) occurs in alkenes when there are different groups attached to the carbon atoms involved in the double bond. For geometrical isomerism to be possible, the following conditions must be satisfied:
- The double-bonded carbon atoms must each have two different substituents.
- This means that if we label the substituents on one carbon as R1 and R2, and on the other carbon as R3 and R4, then R1 must not be equal to R2, and R3 must not be equal to R4.

2. **Structure of 1-Butene**:
- The molecular formula of 1-butene is C4H8. Its structural formula can be represented as:
\[ \text{CH}_2=CH-\text{CH}_2-\text{CH}_3 \]
- In this structure, the double bond is between the first and second carbon atoms.

3. **Identifying Substituents**:
- For the first carbon (C1) of the double bond, we have:
- R1 = H (hydrogen)
- R2 = H (hydrogen)
- For the second carbon (C2) of the double bond, we have:
- R3 = CH2 (ethyl group)
- R4 = CH3 (methyl group)

4. **Checking for Different Groups**:
- Now, we check the groups:
- On C1, both substituents (R1 and R2) are hydrogen atoms, which are identical.
- On C2, the substituents (R3 and R4) are different (ethyl and methyl).
- Since R1 and R2 are identical, the condition for geometrical isomerism is not satisfied.

5. **Conclusion**:
- Since one of the conditions for geometrical isomerism is not met (R1 = R2), we conclude that 1-butene cannot show geometrical isomerism. Therefore, the statement "1-butene cannot show geometrical isomerism" is correct.

### Final Answer:
1-butene cannot show geometrical isomerism because it has identical substituents (hydrogens) on one of the carbon atoms involved in the double bond.

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