IntroductionAlcohols are organic compounds that contain a hydroxyl (-OH) functional group attached to a carbon atom. They can be classified as primary, secondary, or tertiary, depending on the number of carbon atoms attached to the carbon atom with the -OH group. When alcohols are dehydrated, they lose a molecule of water to form an alkene. However, not all alcohols give stable compounds on dehydration. In this context, we will discuss the alcohol that does not give a stable compound on dehydration.AnswerThe alcohol which does not give a stable compound on dehydration is methyl alcohol (also known as methanol or wood alcohol). This is because it is a primary alcohol, meaning that the carbon atom with the -OH group is attached to only one other carbon atom. As a result, on dehydration, it forms a very unstable intermediate carbocation, which can undergo rearrangement to give a variety of products, including alkenes, ethers, and other compounds. Therefore, methyl alcohol is not a good substrate for dehydration reactions.On the other hand, other alcohols like ethyl alcohol, n-propyl alcohol, and n-butyl alcohol give stable compounds on dehydration because they are secondary or tertiary alcohols, meaning that the carbon atom with the -OH group is attached to two or three other carbon atoms, respectively. These alcohols form more stable carbocations on dehydration, which do not undergo rearrangement, leading to the formation of predictable products.ConclusionIn conclusion, methyl alcohol does not give a stable compound on dehydration due to the formation of an unstable intermediate carbocation. Other alcohols like ethyl alcohol, n-propyl alcohol, and n-butyl alcohol give stable compounds on dehydration because they form more stable carbocations, which do not undergo rearrangement.

Dehydration of methyl alcohol gives an unstable intermediate carbene on dehydration. so B is correct option.