The alkene that exhibits geometrical isomerism is : (1) Propene (2) 2-methyl propene (3) 2-butene (4) 2-methyl-2- butene

To determine which alkene exhibits geometrical isomerism, we need to understand what geometrical isomerism is. This type of isomerism occurs in compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of groups around a double bond. For an alkene to show geometrical isomerism, it must have a carbon-carbon double bond (C=C) with different substituents attached to each carbon of the double bond.

Identifying Geometrical Isomerism

Let's analyze the options provided:

• Propene (C3H6): This compound has the structure CH2=CH-CH3. The double bond is between two carbon atoms that both have identical hydrogen atoms attached (CH2 and CH3). Since there are no different groups on either side of the double bond, propene does not exhibit geometrical isomerism.
• 2-Methylpropene (C4H8): The structure is CH2=C(CH3)-CH3. Here, the double bond is between a carbon with a methyl group and another carbon with two hydrogens. Similar to propene, there are no different groups on either side of the double bond, so 2-methylpropene also does not show geometrical isomerism.
• 2-Butene (C4H8): This compound can exist in two forms: cis-2-butene and trans-2-butene. The structure is CH3-CH=CH-CH3. In this case, the two carbon atoms involved in the double bond have different groups attached (one has two hydrogens and the other has two methyl groups). This allows for the possibility of geometrical isomers, making 2-butene a candidate for geometrical isomerism.
• 2-Methyl-2-butene (C5H10): The structure is CH2=C(CH3)-CH2-CH3. Similar to 2-methylpropene, the double bond is between a carbon with a methyl group and another carbon with two hydrogens. Therefore, it does not exhibit geometrical isomerism.

Conclusion on Geometrical Isomerism

From this analysis, the only alkene that exhibits geometrical isomerism is 2-butene. The presence of different substituents on either side of the double bond allows for the formation of cis and trans isomers, which are distinct in their physical and chemical properties. This characteristic is crucial in various chemical reactions and applications, especially in organic synthesis and material science.