Step 1: Understanding the Reaction:
The figure shows 2-chlorobutane (sec-butyl chloride) reacting with magnesium in dry ether, then with ethanol.
Step 2: Step A:
Magnesium inserts into the C-Cl bond to form the Grignard reagent, sec-butylmagnesium chloride, \(\text{CH}_3\text{CH}_2\text{CH(CH}_3)\text{MgCl}\).
Step 3: Step B:
A Grignard reagent is a strong base; the carbon attached to Mg is strongly nucleophilic and carbanion-like. It takes a proton from ethanol, which has an acidic O-H hydrogen:
\[ \text{CH}_3\text{CH}_2\text{CH(CH}_3)\text{MgCl} + \text{C}_2\text{H}_5\text{OH} \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3 + \text{Mg(OC}_2\text{H}_5)\text{Cl} \]
So B is butane, the four-carbon zigzag chain.
Step 4: Why the other options are wrong.
The 2-butanol structure (A) needs oxidation with oxygen, not an alcohol. The Mg-OH compound (C) does not form from ethanol. The branched six-carbon alkane (D) would need coupling of two alkyl groups, which does not happen here.
Final Answer:
Product B is butane, option (B).
\[ \boxed{\text{Butane (B)}} \]
