9. What is the name of the molecule?

3–methyl–2–butanol

Explanation:

To name the compound, we must:

1. Identify the functional group.

2. Give the functional group of the compound the lowest possible count.

3. Locate the longest continuous carbon chain. This gives the parent name of the compound.

4. Identify the substituent group attached.

5. Give the substituent group the lowest possible count.

6. Combine the above to get the name of the compound.

Now, let us obtain the name of the compound.

1. The functional group of the compound is Alcohol i.e —OH.

2. The functional group is located at carbon 2.

3. The longest continuous carbon chain is carbon 4 i.e butane. But the presence of the functional group i.e OH will replace the –e in butane with –ol. Therefore, the compound is butanol.

4. The substituent group attached is methyl i.e CH3.

5. The substituent group is located at carbon 3.

6. Therefore, the name of the compound is:

3–methyl–2–butanol.

i believe the answer is a.