GCSE Chemistry Practice Test 6

Correct: (C)

Protons and neutrons each have a relative mass of 1; electrons have a negligible mass.

Correct: (B)

The atomic (proton) number equals the number of protons, so a calcium atom has 20 protons.

Correct: (A)

Group 7 elements are called the halogens.

Correct: (D)

The later discovery of elements such as gallium, matching his predictions, convinced scientists that his table was correct.

Correct: (A)

Halogens become less reactive down the group because the outer shell is further from the nucleus, so an extra electron is gained less easily.

Correct: (D)

The group number equals the number of electrons in the outer shell, which is 1.

Correct: (B)

Chlorine has two main isotopes, Cl-35 and Cl-37, in roughly a 3:1 ratio, giving an average mass of 35.5.

Correct: (C)

Transition metals and their compounds are often coloured, unlike Group 1 metal compounds, which are usually white.

Correct: (B)

Charge can only be carried through the compound when the charged particles are free to move.

Correct: (A)

In covalent bonding, atoms share pairs of electrons so that each atom achieves a stable outer shell.

Correct: (D)

Diamond is a giant covalent (macromolecular) structure; iodine and water are simple molecular, and sodium chloride is ionic.

Correct: (C)

Fullerenes such as buckminsterfullerene, C60, are hollow spheres or tubes made of carbon atoms.

Correct: (B)

The regular layers of positive ions can slide while the delocalised electrons still hold the structure together.

Correct: (A)

Boiling water only overcomes weak intermolecular forces; the strong O-H covalent bonds stay intact.

Correct: (D)

Because nanoparticles are so small they can pass into the body, so possible risks must be investigated.

Correct: (D)

moles = mass / Mr = 100 / 100 = 1 mol.

Correct: (B)

mass = moles × Mr = 2 × 18 = 36 g.

Correct: (A)

250 cm^3 = 0.25 dm^3, so concentration = 0.5 / 0.25 = 2 mol/dm^3.

Correct: (C)

atom economy = (Mr of desired product / total Mr of all reactants) × 100.

Correct: (D)

volume = 2 × 24 = 48 dm^3.

Correct: (B)

Once the limiting reactant is used up the reaction stops, so it controls the maximum amount of product.

Correct: (A)

percentage = (14 / 17) × 100 = 82%.

Correct: (C)

acid + carbonate → salt + water + carbon dioxide.

Correct: (D)

Sodium is too reactive to be discharged from solution, so hydrogen ions are discharged at the cathode to give hydrogen.

Correct: (A)

Neutral solutions have pH 7 and turn universal indicator green.

Correct: (B)

Nitric acid forms nitrate salts, so the products are potassium nitrate and water.

Correct: (C)

Of these metals, magnesium is highest in the reactivity series and reacts vigorously with dilute acids and with steam.

Correct: (D)

Negative chloride ions move to the positive anode and lose electrons to form chlorine gas.

Correct: (A)

In neutralisation, hydrogen ions from the acid react with hydroxide ions from the alkali to form water.

Correct: (B)

Metals below carbon in the reactivity series can be extracted by reduction with carbon.

Correct: (D)

Endothermic reactions absorb energy, so the surroundings get colder.

Correct: (A)

Bond making releases energy; if this exceeds the energy needed for bond breaking, the overall energy change is negative (exothermic).

Correct: (C)

A non-rechargeable cell stops working when one of its reactants has been consumed.

Correct: (B)

Fuel cells do not need lengthy electrical recharging; they generate electricity for as long as fuel is supplied.

Correct: (D)

The products store the extra energy that has been taken in from the surroundings.

Correct: (A)

mean rate = volume / time = 90 / 30 = 3 cm^3/s.

Correct: (C)

Exposing a larger surface area increases the frequency of collisions with the other reactant.

Correct: (D)

Equilibrium is dynamic: both reactions continue at the same rate, so concentrations stay constant.

Correct: (B)

There are 4 gas molecules on the left and only 2 on the right, so a higher pressure favours the side with fewer molecules.

Correct: (A)

The system acts to oppose the change by using up the extra reactant (Le Chatelier's principle).

Correct: (C)

A higher concentration means more particles per unit volume and therefore a greater collision frequency.

Correct: (B)

Each fraction condenses where the temperature in the column matches its boiling range.

Correct: (C)

Cracking produces shorter alkanes, which are in demand as fuels, and alkenes, which are used to make polymers.

Correct: (A)

The hydration of ethene is the industrial method of making ethanol for solvents and fuels.

Correct: (D)

Condensation polymers such as polyesters form when monomers with two functional groups react together, eliminating water.

Correct: (C)

Alkenes contain one C=C double bond and have the general formula CnH2n.

Correct: (B)

CH4 + 2O2 → CO2 + 2H2O.

Correct: (C)

A pure substance produces a single spot; a mixture separates into two or more spots.

Correct: (A)

Hydrogen burns with a squeaky pop when a lighted splint is placed at the mouth of the tube.

Correct: (D)

Chloride ions react with silver ions to form insoluble white silver chloride.

Correct: (C)

Potassium ions give a lilac (purple) flame colour.

Correct: (B)

Oxygen makes up about 21% of the atmosphere; nitrogen makes up about 78%.

Correct: (A)

Sulfur dioxide released by burning fossil fuels forms acidic solutions in clouds, producing acid rain.

Correct: (D)

Particulates reflect sunlight back into space (global dimming) and can damage the lungs when inhaled.

Correct: (B)

Renewable energy sources release far less carbon dioxide over their life cycle than fossil fuels.

Correct: (C)

The water passes through filter beds that trap insoluble particles; sterilisation is a separate stage.

Correct: (A)

The plants are harvested and burned, and the metal is extracted from the ash; the method is slow but avoids digging up and processing large amounts of rock.

Correct: (D)

Crude oil formed over millions of years and is being used up much faster than it can be replaced.

Correct: (C)

Ammonia is converted into fertilisers such as ammonium nitrate, which improve crop growth.

Correct: (B)

Recycling usually needs much less energy than extraction and preserves finite ore reserves.