Answer :

Sure, let's go through the chemical reactions and identify compounds [tex]$A$[/tex] and [tex]$B$[/tex] step by step.

1. Starting Compound: The initial compound given is propane, indicated by [tex]\( CH_3-CH_2-CH_3 \)[/tex].

2. First Reaction:
- The first reaction involves the addition of water (hydration) in the presence of an acidic catalyst [tex]\( H^+ \)[/tex].

3. Formation of [tex]$A$[/tex]:
- Propane [tex]\( CH_3-CH_2-CH_3 \)[/tex] will react with [tex]\( H_2O \)[/tex] in the presence of [tex]\( H^+ \)[/tex] to form an alcohol. This process introduces a hydroxyl group (-OH) to one of the carbon atoms.
- When propane undergoes hydration, we typically get 1-propanol due to the formation of a primary alcohol, which is more common under such conditions.
- Thus, [tex]$A$[/tex] is [tex]\( CH_3-CH_2-CH_2OH \)[/tex], which is 1-propanol.

4. Second Reaction:
- The compound [tex]$A$[/tex] ([tex]\( CH_3-CH_2-CH_2OH \)[/tex]) is now subjected to an oxidation reaction using [tex]\( CrO_3 \)[/tex].
- Oxidation of a primary alcohol (1-propanol) leads to the formation of a carboxylic acid.
- 1-propanol [tex]\( CH_3-CH_2-CH_2OH \)[/tex] will be oxidized to form propanoic acid [tex]\( CH_3-CH_2-COOH \)[/tex].

5. Formation of [tex]$B$[/tex]:
- Therefore, [tex]$B$[/tex] is [tex]\( CH_3-CH_2-COOH \)[/tex], which is propanoic acid.

In summary:

- Compound [tex]$A$[/tex] is [tex]\( CH_3-CH_2-CH_2OH \)[/tex] (1-propanol).
- Compound [tex]$B$[/tex] is [tex]\( CH_3-CH_2-COOH \)[/tex] (propanoic acid).