Van Der Waals Forces

Which of the following statements about hydrogen bromide (HBr) are correct?

(1) Atoms within its molecules are held together by covalent bonds.

(2) Its molecules are held together by van der Waals’ forces.

(3) Its molecules are held together by hydrogen bonds.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following molecules are held together by van der Waals’ forces and hydrogen bonds?

• Hydrogen sulphide

• Chloromethane

• Carbon dioxide

• Ammonia

Which of the following gives the correct order of boiling points of H₂O, HCl and HF?

• H₂O > HCl > HF

• H₂O > HF > HCl

• HF > HCl > H₂O

• HF > H₂O > HCl

Tags

NGSS.HS-PS1-3

Which of the following gives the correct order of increasing melting point for the substances shown below?

(1) CH₃CH₂CH₂CH₃

(2) CH₃CH₂CH₂CH₂CH₃

(3) CH₃CH₂CH₂CH₂OH

• (1), (2), (3)

• (2), (1), (3)

• (3), (2), (1)

• (3), (1), (2)

Tags

NGSS.HS-PS1-1

The ability of a liquid to flow is linked to the strength of its intermolecular forces. Suggest which of these liquids flows the slowest when poured.

• Propane-1,2,3-triol

• Propane-1,2-diol

• Pentane

• Butane

Consider the following molecule:

How many hydrogen atoms in this molecule can form hydrogen bonds?

• 1

• 4

• 5

• 6

Which of the following statements about ethanoic acid are correct?

(1) The atoms in the molecule are held together by covalent bonds.

(2) The molecules are held together by van der Waals’ forces.

(3) The molecules are held together by hydrogen bonds.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

C₂H₆, CH₃OH and CH₃F are three compounds with comparable molecular masses. Which of the following shows the ascending order of their boiling points?

• C₂H₆ < CH₃OH < CH₃F

• CH₃F < CH₃OH < C₂H₆

• CH₃OH < CH₃F < C₂H₆

• C₂H₆ < CH₃F < CH₃OH

Tags

NGSS.HS-PS1-3

NGSS.HS-PS3-4

Which of the following statements about water (H₂O) and hydrogen peroxide (H₂O₂) are correct?

(1) Both water and hydrogen peroxide consist of polar molecules.

(2) Hydrogen bonds exist between water molecules and hydrogen peroxide molecules respectively.

(3) Hydrogen peroxide has a higher boiling point than water.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Substance X is composed of discrete molecules. The melting point of X is 260 K and the boiling point is 380 K. X is soluble in non-polar solvents and insoluble in aqueous solvents. Which of the following deductions concerning X is INCORRECT?

• X must not be able to conduct electricity.

• X must contain hydrogen and carbon only.

• X must not form hydrogen bonds with molecules.

• X must be a liquid at room conditions.