Attempt this paper, then reveal the answers to mark yourself.
Section A — Objective
The smallest particle of an element that can take part in a chemical reaction is the
Answer: A. An atom is the smallest particle of an element that takes part in a chemical reaction.
A substance that produces hydrogen ions in solution is a/an
Answer: A. An acid produces H⁺ ions in solution. A base produces OH⁻ (or neutralises an acid).
Which group of the periodic table contains the noble gases?
Answer: C. Noble gases (helium, neon, argon) are in Group 8/0.
The process of decomposing an electrolyte by passing an electric current is called
Answer: A. Electrolysis decomposes an electrolyte using a direct current.
The number of particles in one mole of a substance (Avogadro’s number) is
Answer: A. One mole contains 6.02 × 10²³ particles (Avogadro’s number).
Which of the following is an organic compound?
Answer: C. Ethanol (C₂H₅OH) is an organic (carbon) compound. CO₂ and carbonates are not considered organic.
Section B — Theory
Write a balanced equation for the reaction between sodium hydroxide and hydrochloric acid.
Answer: NaOH + HCl → NaCl + H₂O (neutralisation to form salt and water).
Calculate the molar mass of sulphuric acid, H₂SO₄ (H = 1, S = 32, O = 16).
Answer: Mᵣ = (2 × 1) + 32 + (4 × 16) = 2 + 32 + 64 = 98 g/mol.
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