In order for a substitution reaction to take place, at a minimum, and are needed. carbocation rearrangement proton transfer loss of a leaving group nucleophilic attack

In order for a substitution reaction to take place, at a minimum, loss of a leaving group and nucleophilic attack are needed.

Explanation:

When one group in a molecule is replaced by another one then it is called a substitution reaction.

For a substitution reaction reaction to occur at a minimum, it is necessary to have a leaving group that helps in creating a carbocation and hence a nucleophile can easily attack.

For example,

Thus, we can conclude that in order for a substitution reaction to take place, at a minimum, loss of a leaving group and nucleophilic attack are needed.

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a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.