Which of the following compounds can be represented by the molecular formula C2 H6O?

Analyze the question: We need the compound whose molecular formula is C₂H₆O. Check each option's formula.

Concept: The molecular formula tells us the exact number of each atom in one molecule. Work out each compound's formula from its name.

Solution:

• A. Propanal has 3 carbons, with the aldehyde group –CHO: CH₃CH₂CHO = C₃H₆O. It has 3 carbons, so it does not match.
• B. Ethanol is CH₃CH₂OH. Carbons: 2. Hydrogens: 3 + 2 + 1 = 6. Oxygen: 1. So it is C₂H₆O. This matches.
• C. Methanoic acid is HCOOH = CH₂O₂. It does not match.
• D. Glucose is C₆H₁₂O₆. It does not match.

Answer: Option B, ethanol.

Tip: Learn the general formula for alkanols, CₙH₂ₙ₊₁OH. For n = 2: C₂H₅OH, which is C₂H₆O. Also remember that the name's prefix gives the carbon count (meth = 1, eth = 2, prop = 3, but = 4). Propanal has "prop", so it must have 3 carbons and cannot be C₂H₆O. Note that dimethyl ether (CH₃OCH₃) is also C₂H₆O, as an isomer of ethanol, but it is not among the options here.