A-Level Chemistry 2

Question 1

What is the pH of a 0.01 mol/dm³ solution of hydrochloric acid?

Accepted Answer

2

Answer

HCl is a strong acid that fully dissociates: [H⁺] = 0.01 = 10⁻² mol/dm³. pH = -log₁₀[H⁺] = -log₁₀(10⁻²) = 2.

Question 2

What is the test for an aldehyde using Tollens' reagent?

Accepted Answer

A silver mirror forms on the test tube walls

Answer

Tollens' reagent (ammoniacal silver nitrate) is reduced by aldehydes to form metallic silver, which deposits as a mirror-like coating on the test tube. This is the 'silver mirror test'.

Question 3

What is the molecular geometry of SF₆ according to VSEPR theory?

Accepted Answer

Octahedral

Answer

SF₆ has six bonding pairs around the central sulphur atom and no lone pairs, giving an octahedral geometry with 90° bond angles.

Question 4

In electrochemistry, what happens at the cathode during electrolysis?

Accepted Answer

Reduction occurs — cations gain electrons

Answer

At the cathode (negative electrode), cations are attracted and gain electrons (reduction). Remember: 'CATions go to the CAThode' and 'Reduction at the Cathode'.

Question 5

What is a peptide bond in the context of A-Level organic chemistry?

Accepted Answer

A covalent bond formed between the amino group of one amino acid and the carboxyl group of another through a condensation reaction

Answer

A peptide bond (-CO-NH-) forms through a condensation reaction between the -NH₂ group of one amino acid and the -COOH group of another, releasing a molecule of water.

GCE A-Level Practice Test

GCE A-Level Practice Test

A-Level Chemistry 2