5A_QA5 (D2, Mar 9)

Which of the following statements about pentane and dimethylpropane are correct?

(1) They have the same molecular formula.

(2) Pentane is a straight-chain alkane while dimethylpropane is a branched-chain alkane.

(3) The van der Waals’ forces among pentane molecules are weaker than those among dimethylpropane molecules.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following compounds is the least soluble in water?

• Propan-1-ol

• Propanoic acid

• 1-chloropropane

• Propane

Which of the following compounds are miscible in water?

(1) Propan-2-ol

(2) Butanoic acid

(3) 1-iodobutane

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following series of compounds does NOT have hydrogen bonds between their molecules?

• Primary amines

• Alcohols

• Ketones

• Carboxylic acids

Which of the following statements about unsubstituted amides and primary amines are INCORRECT ?

(1) Both of them are acid derivatives.

(2) Both of them are nitrogen-containing carbon compounds.

(3) Both of them have higher boiling points than carboxylic acids with a similar relative molecular mass.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following is the correct order of decreasing boiling points of the organic compounds?

• Ethanoic acid > ethanol > ethanamide > chloroethane

• Chloroethane > ethanoic acid > ethanamide >ethanol

• Ethanol > chloroethane > ethanoic acid > ethanamide

• Ethanamide > ethanoic acid > ethanol > chloroethane

Which of the following statements about unsubstituted amides is INCORRECT ?

• The general formula of unsubstituted amides is RCONH₂, where R is a hydrogen atom or an alkyl group.

• The boiling points of amides are higher than those of carboxylic acids with a similar relative molecular mass.

• The intermolecular forces between unsubstituted amide molecules are hydrogen bonds only.

• Lower members of the series are soluble in water.

Which of the following statements about primary amines are correct?

(1) The general formula of primary amines is RNH₂, where R is an alkyl group.

(2) Pentan-3-amine is an example of primary amines.

(3) Each amino group (-NH₂) can form a maximum of three hydrogen bonds with water molecules.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following statements about the first member of the aldehyde series is INCORRECT ?

• Its condensed structural formula is HCHO.

• It is insoluble in water.

• Its trivial name is formaldehyde.

• It can be used in the production of polymers.

Which of the following statements about ethanoic acid is INCORRECT ?

• It exists as dimers in the gaseous state.

• Its trivial name is acetic acid.

• It is miscible in water in all proportions.

• It has a lower boiling point than ethyl ethanoate.