2025 O Level Pure Chemistry Paper 1 — All Solutions

To determine the rate of reaction, a scientist measures the volume of gas produced from the reaction between the acid an…

Which method is used to dry and collect ammonia gas? [Mᵣ: ammonia, 17]…

The table shows the solubilities of solids X and Y in four solvents. A student wants to separate solids X and Y from a m…

Aqueous silver nitrate is mixed with aqueous sodium chloride. How is a pure sample of silver chloride separated from the…

Which statement about Rᶠ values in paper chromatography is correct?…

A sample of gas X is released in one corner of a room. What affects the rate of diffusion of gas X? 1 the empirical form…

Which row is correct?…

How many covalent bonds are there in the molecule with the formula CH₂CHCH₃?…

Which statement is correct?…

Which statement is correct?…

0.50 mol of propane gas is completely combusted. What is the total number of electrons shared by the covalent bonds in t…

One phosphorus pentachloride molecule, PCl₅, reacts with one ethanol molecule. The products of this reaction are one chl…

Complete combustion of a sample of hydrocarbon Z produces 4.4 g of carbon dioxide and 2.7 g of water as the only product…

1.0 g of each of the metals calcium, iron, magnesium and zinc is placed in separate test-tubes, each containing excess d…

A 20.0 g sample of impure calcium carbonate is added to 0.400 mol of hydrochloric acid. The impurities do not react with…

When dilute sulfuric acid and aqueous sodium hydroxide react, sodium hydrogen sulfate, NaHSO₄, is first formed. H₂SO₄(aq…

Which substance, when added to water, will cause the concentration of hydrogen ions to be lower than that of hydroxide i…

Which solid is insoluble in water?…

Barium oxide, BaO, reacts with water to produce barium hydroxide, Ba(OH)₂. Barium hydroxide and barium nitrate, Ba(NO₃)₂…

Ammonia is manufactured in the Haber Process. The graph shows the percentage yield of ammonia as the temperature and pre…

An aqueous solution of compound X forms a green precipitate when a few drops of aqueous sodium hydroxide are added. When…

Four mixtures are listed. 1 aqueous barium nitrate and aqueous sodium sulfate. 2 copper and dilute hydrochloric acid. 3 …

Four statements about oxidising and reducing agents are listed. 1 Aqueous potassium iodide is used to test for oxidising…

Three different compounds are electrolysed. Which experiments will result in a change in mass of both of the electrodes?…

Three different compounds are electrolysed. [Three cells: experiment 1 — Pt electrodes in concentrated NaCl(aq); experim…

Which chemical change generates electricity directly in a hydrogen fuel cell?…

Which property decreases across Period 3 from sodium to argon?…

Three statements about radon are listed. 1 It is a non-metallic gas. 2 It has a full outer shell of electrons. 3 It has …

A list of properties is shown: low melting point; low density; high electrical conductivity; forms compounds with variab…

Which statement about the extraction of metals from their ores is correct?…

An energy profile diagram for a reaction is shown. Which statement about the diagram is correct?…

Which statement about a catalyst is correct?…

The rate of three reactions is investigated by measuring the amount of carbon dioxide produced over time. Reaction X pro…

Which structure shows a substance used as a biofuel?…

Pent-2-ene has the structure CH₃CH=CHCH₂CH₃. Four other hydrocarbons are shown. Which hydrocarbons are structural isomer…

What is the structure of the compound formed when butanol is oxidised using acidified potassium manganate(VII)?…

Three statements about ethanol are listed. 1 When ethanol is made by the fermentation of glucose, a larger molecule is b…

How many molecules of water are needed to depolymerise this polymer?…

Four sources of atmospheric pollutants are listed. 1 lightning. 2 volcanoes. 3 combustion of fossil fuels. 4 release of …

CFCs and carbon monoxide, CO, are atmospheric pollutants. Which row describes one negative effect of each pollutant?…