How many chirality centers are present in $2_{\text{-}}\text{chlorobutane}$?

• A. $2$
• B. $4$
• C. $1$
• D. $0$

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the structure of 2-chlorobutane. It is a four-carbon chain (butane) with a chlorine atom attached to the second carbon.
2. Step 2: Identify what a chirality center (chiral center) is: a carbon atom bonded to four different groups.
3. Step 3: Examine each carbon in 2-chlorobutane to see if it has four different substituents. Focus especially on the second carbon where the chlorine is attached.
4. Step 4: For the second carbon, check the groups attached: a chlorine atom, a hydrogen atom, a methyl group (CH3), and an ethyl group (CH2CH3). Since all four groups are different, this carbon is a chiral center.
5. Step 5: Verify the other carbons do not have four different groups attached, confirming that there is only one chirality center in 2-chlorobutane.