What is a propagation step in the radical substitution mechanism of ethane with chlorine?

CHEMISTRY · Single correct · A Level · Chemistry · Alkanes · Alkanes

Problem

What is a propagation step in the radical substitution mechanism of ethane with chlorine? (1)

\text{Cl}_2 \rightarrow 2\text{Cl}\cdot

(2)

\cdot\text{C}_2\text{H}_5 + \text{Cl}_2 \rightarrow \text{C}_2\text{H}_5\text{Cl} + \text{Cl}\cdot

(3)

\cdot\text{C}_2\text{H}_5 + \text{Cl}\cdot \rightarrow \text{C}_2\text{H}_5\text{Cl}

(4)

\text{C}_2\text{H}_6 + \text{Cl}\cdot \rightarrow \text{C}_2\text{H}_5\text{Cl} + \cdot\text{H}