How many products (including stereoisomers) are expected from monochlorination of the following compound?

The correct option is 6.

The given compound shown in the image is isopentane (also known as 2-methylbutane):
$({\mathrm{CH}}_3{)}_2\mathrm{CH}-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

To determine the total number of monochlorination products (including stereoisomers), we identify the different types of hydrogen atoms available for substitution in 2-methylbutane:

1. Substitution at the C-1 methyl groups (the two equivalent $-{\mathrm{CH}}_3$ groups on C-2):
Substituting a hydrogen atom on either of these methyl groups yields:
${\mathrm{CH}}_2\mathrm{Cl}-{\mathrm{CH}}^{*}\left({\mathrm{CH}}_3\right)-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
(1-chloro-2-methylbutane)
In this product, the C-2 carbon atom becomes a chiral center (marked with an asterisk *). Therefore, this compound exists as a pair of enantiomers:
• $d$-1-chloro-2-methylbutane
• $l$-1-chloro-2-methylbutane
This contributes 2 stereoisomers.

2. Substitution at the C-2 position ($-\mathrm{CH}-$ group):
Substituting the hydrogen atom at the C-2 position yields:
$({\mathrm{CH}}_3{)}_2\mathrm{CCl}-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
(2-chloro-2-methylbutane)
This molecule does not possess any chiral center and is achiral.
This contributes 1 product.

3. Substitution at the C-3 position ($-{\mathrm{CH}}_2-$ group):
Substituting a hydrogen atom at the C-3 position yields:
$({\mathrm{CH}}_3{)}_2\mathrm{CH}-{\mathrm{CHCl}}^{*}-{\mathrm{CH}}_3$
(2-chloro-3-methylbutane)
In this product, the C-3 carbon atom becomes a chiral center (marked with an asterisk *). Therefore, this compound exists as a pair of enantiomers:
• $d$-2-chloro-3-methylbutane
• $l$-2-chloro-3-methylbutane
This contributes 2 stereoisomers.

4. Substitution at the C-4 methyl group ($-{\mathrm{CH}}_3$ group at the end of the chain):
Substituting a hydrogen atom at the C-4 position yields:
$({\mathrm{CH}}_3{)}_2\mathrm{CH}-{\mathrm{CH}}_2-{\mathrm{CH}}_2\mathrm{Cl}$
(1-chloro-3-methylbutane)
This molecule does not possess any chiral center and is achiral.
This contributes 1 product.

Total Number of Products:
Adding up the products from all positions:
$2+1+2+1=6$

Thus, a total of 6 monochlorinated products (including stereoisomers) are expected.