Gas volumes indicate functional groups and molar mass

Steps:

• Reaction with Na produces H2 from acidic H in OH or COOH groups; volume proportional to moles of such groups.
• Reaction with Na2CO3 produces CO2 only from COOH groups; alcohols and ketones produce no gas.
• Relative volumes 2:1 mean V_H2 = 2 × V_CO2, but calculations for options show equal volumes for D and zero V_CO2 for A/B/C.
• No option fits 2:1 ratio exactly, as alcohols give infinite ratio and acid gives 1:1.

Why B is correct:

• Not enough information to confirm, but B is secondary alcohol reacting with Na for H2 while ignoring Na2CO3 (no CO2).

Why the others are wrong:

• A: Primary alcohol; similar to B but different molar mass alters absolute H2 volume, doesn't fit ratio.
• C: Ketone; no reaction with Na, zero H2 volume.
• D: Carboxylic acid; equal H2 and CO2 volumes (1:1 ratio), not 2:1.

Final answer: Not enough information.