What determines the number of isomers produced when adding water to unsymmetrical alkenes?

The number of isomers produced when adding water to unsymmetrical alkenes is primarily determined by whether the alkene is symmetrical or unsymmetrical. When water adds to an unsymmetrical alkene through the process known as hydration, the reaction can yield different products based on the orientation of the addition.

In the case of unsymmetrical alkenes, there are typically two different carbocations that can form as intermediates during the addition of water. These carbocations can lead to different alcohols, depending on which side of the double bond the hydroxyl group (OH) from the water molecule attaches to. The distinction between symmetrical and unsymmetrical alkenes becomes crucial because symmetrical alkenes will yield the same product no matter where the addition occurs, leading to just one product.

In contrast, unsymmetrical alkenes allow for the creation of multiple isomers due to the different possible orientations of the hydroxyl group and hydrogen atom that can be added across the double bond. This is a direct result of the structure of the alkene and the arrangement of its substituents, which influences the regioselectivity of the addition reaction.

The factors mentioned in the other options, such as temperature and nature of the acid, may