The smallest alkane which can shown optical isomerism possesses:

Options

A. 5 carbons
B. 6 carbons
C. 7 carbons
D. 8 carbons

Answer

To solve the question regarding the smallest alkane that can show optical isomerism, we need to follow these steps:

### Step 1: Understand Optical Isomerism
Optical isomerism occurs when a molecule has a chiral center, which is a carbon atom bonded to four different groups. This results in non-superimposable mirror images, known as enantiomers.

**Hint:** Remember that for a carbon to be chiral, it must have four different substituents.

### Step 2: Identify the Smallest Alkane
The smallest alkane is methane (CH₄), but it cannot show optical isomerism because it does not have a chiral center. The next alkanes are ethane (C₂H₆), propane (C₃H₈), and butane (C₄H₁₀), none of which have chiral centers.

**Hint:** List the first few alkanes and check for the presence of a chiral center.

### Step 3: Determine the Structure of Larger Alkanes
As we move to larger alkanes, we need to find the first alkane that has a chiral center. The first candidate is 2-pentene (C₅H₁₀) or 2-methylbutane (C₅H₁₁). However, we need to consider the structure of alkanes.

**Hint:** Draw the structures of alkanes with increasing carbon numbers to find the first one with a chiral center.

### Step 4: Identify the Chiral Center
For an alkane to have a chiral center, it needs to have a carbon atom bonded to four different groups. The smallest alkane that meets this criterion is 2-pentanol (C₅H₁₂), which has a chiral center at the second carbon.

**Hint:** Look for a carbon that has four different substituents attached to it.

### Step 5: Conclusion
The smallest alkane that can show optical isomerism is 2-pentanol (C₅H₁₂), which has a chiral center. Therefore, the answer to the question is that the smallest alkane which can show optical isomerism possesses **7 carbon atoms**.

**Final Answer:** Option C is correct.