GCSE Chemistry Practice Test 18

Correct: (C)

Atomic number 6 means the atom has 6 protons, which is carbon.

Correct: (A)

A neutron has no charge and a relative mass of about 1.

Correct: (D)

Relative atomic mass accounts for the masses and abundances of an element's isotopes.

Correct: (B)

Chlorine has 7 electrons in its outer shell, so it is in Group 7.

Correct: (C)

Halogens become less reactive down the group because the outer electron is gained less easily.

Correct: (D)

Many transition metal compounds are coloured, and transition metals or their compounds are often catalysts.

Correct: (A)

The proton number defines the element; atoms of the same element have the same number of protons.

Correct: (B)

Elements are arranged by increasing atomic (proton) number.

Correct: (D)

Magnesium oxide has a giant ionic structure with strong attractions in all directions.

Correct: (B)

Water consists of small covalent molecules with weak forces between the molecules.

Correct: (A)

Polymer molecules have strong covalent bonds along the chain and weaker intermolecular forces between chains.

Correct: (C)

Graphene is one atom thick and consists of carbon atoms in a hexagonal lattice.

Correct: (A)

In metals, layers of positive ions can slide while the delocalised electrons maintain bonding.

Correct: (D)

Silicon dioxide has a giant covalent network of strongly bonded atoms.

Correct: (B)

Fullerenes are carbon molecules shaped as hollow balls, tubes or similar structures.

Correct: (C)

Moles = mass ÷ Mr = 7.3 ÷ 36.5 = 0.20 mol.

Correct: (B)

Mr = (2 × 1) + 32 + (4 × 16) = 98.

Correct: (A)

8.0 g CuO = 0.10 mol, which forms 0.10 mol Cu; mass = 0.10 × 64 = 6.4 g.

Correct: (D)

500 cm^3 = 0.500 dm^3, so concentration = 10 ÷ 0.500 = 20 g/dm^3.

Correct: (C)

Percentage yield = (45 ÷ 50) × 100 = 90%.

Correct: (B)

Atom economy = (95 ÷ 97) × 100 = 97.9%.

Correct: (D)

Volume = 2.0 × 24 = 48 dm^3.

Correct: (A)

Universal indicator is red in strongly acidic solutions.

Correct: (D)

Acid + alkali → salt + water.

Correct: (C)

Copper oxide reacts with sulfuric acid; excess solid is filtered off and the filtrate is crystallised.

Correct: (B)

Hydrogen ions are discharged at the cathode to form hydrogen gas.

Correct: (A)

Zinc is more reactive than copper, so it displaces copper from copper sulfate solution.

Correct: (C)

Adding alkali neutralises acid, so the pH rises; excess alkali makes the solution alkaline.

Correct: (D)

Chloride ions are discharged at the anode to form chlorine gas.

Correct: (B)

Insoluble salts are made by precipitation, followed by filtration, washing and drying.

Correct: (D)

In an exothermic reaction the products have less energy than the reactants; the difference is released.

Correct: (A)

A temperature fall indicates that energy is absorbed from the surroundings, so the reaction is endothermic.

Correct: (C)

Hydrogen fuel cells combine hydrogen and oxygen to produce water and electrical energy.

Correct: (B)

Energy to break bonds = 945 + (3 × 436) = 2253 kJ; energy released forming bonds = 6 × 391 = 2346 kJ; ΔH = 2253 – 2346 = -93 kJ/mol.

Correct: (A)

Activation energy is the minimum energy needed for a collision to result in a reaction.

Correct: (C)

Rate can be found by measuring how quickly gas is produced, for example using a gas syringe.

Correct: (B)

Higher pressure pushes gas particles closer together, increasing collision frequency.

Correct: (D)

Increasing surface area exposes more particles to collisions with the other reactant.

Correct: (A)

The equilibrium shifts in the direction that partly counteracts the change, using up some added reactant.

Correct: (D)

A catalyst speeds up both forward and reverse reactions equally, so the position does not change.

Correct: (C)

Heating favours the endothermic forward reaction, producing white anhydrous copper sulfate and water.

Correct: (A)

Each fraction condenses at a different temperature range because the hydrocarbons boil at different temperatures.

Correct: (D)

Alkenes react with bromine in an addition reaction, removing the orange colour.

Correct: (B)

Complete combustion of a hydrocarbon in plenty of oxygen forms carbon dioxide and water.

Correct: (C)

Carboxylic acids contain the -COOH functional group.

Correct: (A)

Addition polymerisation uses unsaturated monomers whose double bonds open so chains can form.

Correct: (B)

Alcohols react with carboxylic acids to form esters and water.

Correct: (D)

Formulations are mixtures made to a set recipe so the product has the required properties.

Correct: (C)

Hydrogen burns with a squeaky pop when mixed with air and ignited by a lit splint.

Correct: (A)

Rf = distance moved by substance ÷ distance moved by solvent = 7.5 ÷ 10.0 = 0.75.

Correct: (B)

Barium sulfate is white and insoluble; acid is added first to remove carbonate ions that could interfere.

Correct: (A)

Intense volcanic activity released gases, producing an early atmosphere rich in carbon dioxide.

Correct: (C)

Photosynthesis uses carbon dioxide and releases oxygen, changing the atmosphere over long periods.

Correct: (A)

The high temperature in engines provides enough energy for nitrogen and oxygen in air to react.

Correct: (B)

Fine carbon particles can damage lungs and reflect sunlight, reducing light reaching the surface.

Correct: (C)

Sewage treatment includes removing solids, settling, and using microbes to break down organic material.

Correct: (D)

Phytomining uses plants to absorb metal compounds from low-grade ores or contaminated land.

Correct: (A)

Most ammonia from the Haber process is used to make nitrogen-based fertilisers.

Correct: (B)

LCAs can involve subjective decisions, such as how serious different environmental effects are.

Correct: (D)

Sea water can be desalinated by distillation or by reverse osmosis through membranes.