Step 1: Oxidation of 2-methylpropane
The starting material in the reaction sequence is 2-methylpropane (\( (CH_3)_2CH_2 \)). Upon oxidation, 2-methylpropane can first form an intermediate ketone, acetone (\( (CH_3)_2C=O \)), as a result of the loss of two hydrogen atoms from the primary carbon.
Step 2: Further Oxidation and Cleavage
After the formation of acetone, the next step involves further oxidation, which breaks the bond between the two carbons, resulting in the formation of formaldehyde (\( CH_2=O \)).
Step 3: Identifying Products A and B
- A is acetone (\( (CH_3)_2C=O \)) because it is the ketone formed during oxidation.
- B is formaldehyde (\( CH_2=O \)) because it is the product formed after further oxidation and cleavage.
Thus, the correct answer is:
\[
\boxed{(2) \ (CH_3)_2C=O, CH_2=O}
\]
\vspace{0.5cm}