Question

In which of the following molecules carbon atom marked with asterisk (*) is asymmetric?

(a) \[\begin{array}{cc}
\ce{H}\\
|\\
\phantom{.}\ce{C^*}\phantom{}\\
\phantom{}/\phantom{..}|\phantom{..}\backslash\phantom{}\\
\phantom{.}\ce{I}\phantom{...}\ce{Br}\phantom{..}\ce{Cl}
\end{array}\]

(b) \[\begin{array}{cc}
\ce{D}\\
|\\
\phantom{.}\ce{C^*}\phantom{}\\
\phantom{}/\phantom{..}|\phantom{..}\backslash\phantom{}\\
\phantom{.}\ce{I}\phantom{...}\ce{Br}\phantom{..}\ce{Cl}
\end{array}\]

(c) \[\begin{array}{cc}
\ce{H}\\
|\\
\phantom{.}\ce{C^*}\phantom{}\\
\phantom{}/\phantom{..}|\phantom{..}\backslash\phantom{}\\
\phantom{..}\ce{OH}\phantom{..}\ce{C2H5}\phantom{}\ce{CH3}
\end{array}\]

(d) \[\begin{array}{cc}
\ce{H}\\
|\\
\phantom{.}\ce{C^*}\phantom{}\\
\phantom{}/\phantom{..}|\phantom{..}\backslash\phantom{}\\
\phantom{..}\ce{H}\phantom{...}\ce{C2H5}\phantom{}\ce{CH3}
\end{array}\]

Options

• (a), (b), (c), (d)

• (a), (b), (c)

• (b), (c), (d)

• (a), (c), (d)

Answer 1

(a), (b), (c)

Explanation:

 Asymmetric/chiral carbon atom is that in which all of its four valencies with four different groups or atoms.

In molecules (a), (b) and (c), all have asymmetric carbon as each carbon has satisfied all four valencies with four different groups or atoms.

In molecule (d), carbon satisfies two of its valencies with two hydrogen atoms i.e., similar atom. So, it is not an asymmetric carbon atom.