The halogen exchange reaction among the following is exhibited by:  

1.   \(\begin{aligned}RX \ + \ NaI \ \xrightarrow[]{\textbf{Acetone}} \ RI \ + \ NaX \\ \\ \end{aligned} \)
2. 
3. 
4. 

Hint: One halogen substitute another halogen

In a halogen exchange reaction, one halogen gets change by another halogen. The reaction in which halogen exchange takes

place is known as the Finkelstein reaction. The reaction is as follows:

RX + NaI → RI + NaX