Dehydration of alcohols to symmetrical ethers with conc. H2SO4

Steps:

• Identify the reaction: primary alcohols heated with excess conc. H2SO4 form symmetrical dialkyl ethers (ROR) via intermolecular dehydration.
• Determine product formula: for C4H10O ether, starting alcohol must be C2H5OH, yielding (C2H5)2O.
• Evaluate choices: assume A, C, D are C4 alcohols (e.g., butanols) producing C8 ethers; B is ethanol, producing C4 ether.
• Confirm single product: symmetrical ether from identical alcohol molecules yields one product.

Why B is correct:

• Ethanol (B) forms only diethyl ether (C4H10O) per the ether formation law for primary alcohols.

Why the others are wrong:

• A: C4 alcohol yields C8H18O ether, not C4H10O.
• C: Branched C4 alcohol yields mixed or C8 ether, not single C4H10O.
• D: Secondary/tertiary C4 alcohol dehydrates to alkene (C4H8), not C4H10O ether.

Not enough information on exact structures, but B fits standard case.

Final answer: B