Step 1: Addition of HCl to propene.
Propene is
\[
CH_3-CH=CH_2
\]
When HCl is added, the reaction follows Markovnikov's rule.
Hydrogen attaches to the carbon atom having more hydrogen atoms, while chlorine attaches to the more substituted carbon atom.
Therefore,
\[
CH_3-CH=CH_2 + HCl
\rightarrow
CH_3-CH(Cl)-CH_3
\]
The product formed is
\[
2\text{-chloropropane}
\]
Step 2: Apply Swarts reaction.
Swarts reaction converts alkyl chlorides or alkyl bromides into alkyl fluorides using metallic fluorides such as:
\[
AgF,\ Hg_2F_2,\ SbF_3,\ CoF_2
\]
Thus,
\[
CH_3-CH(Cl)-CH_3
\xrightarrow{\text{Swarts reaction}}
CH_3-CH(F)-CH_3
\]
Step 3: Identify the final product.
The product obtained is
\[
2\text{-fluoropropane}
\]
Step 4: Final conclusion.
Hence, the major product formed is
\[
\boxed{\text{2-Fluoropropane}}
\]
Therefore, the correct option is
\[
\boxed{(3)}
\]