Correct Option: (A) 2-Bromobutane

Step 1 (Governing Principle & Definition): [0.25 Mark]

A molecule is defined as chiral if it contains at least one chiral center (asymmetric carbon atom). A chiral center is a carbon atom bonded to four different groups or atoms. Mathematically, if a carbon atom is bonded to substituents $a, b, c,$ and $d$, it is chiral if $a \neq b \neq c \neq d$.

Step 2 (Step-by-Step Structural Analysis): [0.5 Mark]

We analyze the structural formulas of the given haloalkanes to identify the presence of a chiral carbon ($C^*$):

• 1-Bromobutane: $CH_3-CH_2-CH_2-CH_2-Br$. No carbon is bonded to four different groups.
• 2-Bromopropane: $CH_3-CH(Br)-CH_3$. The central carbon is bonded to two identical $-CH_3$ groups. Not chiral.
• 1-Bromopropane: $CH_3-CH_2-CH_2-Br$. No carbon is bonded to four different groups.
• 2-Bromobutane: $CH_3-\overset{\displaystyle *}{C}H(Br)-CH_2-CH_3$. The central carbon is bonded to four distinct groups: $$ -H, -Br, -CH_3, \text{ and } -CH_2CH_3 $$ Since all four groups are unique, the carbon atom is chiral.

Step 3 (Final Concluded Answer): [0.25 Mark]

Based on the structural analysis, 2-Bromobutane is the only molecule among the choices that possesses a chiral center. Therefore, the correct option is (A).

💡 EL10 Concept Insight:

Think of a chiral carbon like a person's hands; just like your left and right hands are mirror images but can't perfectly overlap, a chiral carbon is a "hub" connected to four completely different things, making the whole molecule lopsided and unique in its 3D shape.