Step 1: Classify propan-2-ol.
Propan-2-ol has the structure $CH_3$-$CH(OH)$-$CH_3$. The carbon bearing the $-OH$ group is bonded to two other carbon atoms, making this a secondary alcohol.
Step 2: Recall oxidation rules for alcohols.
Primary alcohols oxidise to aldehydes and then to carboxylic acids. Secondary alcohols oxidise only to ketones. Tertiary alcohols resist oxidation under mild to moderate conditions.
Step 3: Apply the rule.
$CrO_3$ is a strong oxidising agent. When it acts on the secondary alcohol propan-2-ol, it removes two hydrogen atoms (one from $-OH$ and one from the $\alpha$-CH) to form a carbonyl compound. Since the product retains two alkyl groups on the carbonyl carbon, it is a ketone.
Step 4: Name the product.
A three-carbon ketone with the carbonyl at position 2 is propanone (acetone): $CH_3$-$CO$-$CH_3$.
\[ \boxed{\text{Propanone}} \]