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2020 O Level Pure Chemistry Paper 1 — All Solutions

40 multiple-choice questions · Free video solutions

Experimental Techniques / Measuring Temperature Change

When an excess of dilute acid is added to a known quantity of sodium carbonate, the temperature of the mixture changes. …

Collection of Gases / Air Composition

Oxygen is prepared by the decomposition of hydrogen peroxide, in the presence of manganese(IV) oxide. The oxygen is coll…

Qualitative Analysis / Tests for Ions and Gases

The following substances are used in the laboratory to test for various ions and gases. acidified potassium manganate(VI…

Purity / Separation Techniques

A colourless substance is made in an experiment. Which are possible methods to determine if this substance is pure? 1 Me…

Diffusion / Kinetic Particle Theory

The rate of diffusion of two gases is measured at different temperatures but at constant pressure. Which would diffuse m…

Atomic Structure / Nucleon and Proton Number

A new element was first synthesised in 2006. It has been given the name oganesson and is represented by ²⁹⁴₁₁₈Og. Which …

Atomic Structure / Ions and Electronic Structure

Four elements are shown as P, Q, R and S. The letters do not represent the chemical symbols of the elements. Which atom …

Structure and Bonding / Giant Covalent Structures

Which two substances have similar three-dimensional arrangements of their atoms?…

Stoichiometry / Percentage Composition

Which compound contains the highest percentage of sulfur by mass?…

Stoichiometry / Mole Calculations

On heating, the carbonate of element X decomposes. XCO₃(s) → XO(s) + CO₂(g) 6.25 g of XCO₃ is heated and 1.2 dm³ of carb…

Stoichiometry / Mole Calculations

The formula of an oxide of element Y is Y₂O₃. 8.0 g of Y₂O₃ contains 5.6 g of Y. How many moles of Y does 5.6 g of the e…

Electrolysis / Products of Electrolysis

Three different compounds are electrolysed. Which experiments produce a gas at the negative electrode?…

Electrochemistry / Simple Cells

The diagram shows a cell. Which statement about the cell is correct?…

Energetics / Activation Energy

A reversible reaction is exothermic in the forward direction and the heat given out is 196 kJ/mol. The activation energy…

Energetics / Bond Energy and Enthalpy Change

Hydrogen burns in air to form water as shown. 2H₂(g) + O₂(g) → 2H₂O(l) Which statement concerning the enthalpy change, Δ…

Rate of Reaction / Catalysts and Energy Profiles

The energy profile diagram for a reaction is shown. A catalyst was added and no other reaction condition was changed. Wh…

Rate of Reaction / Effect of Concentration

A sample of 0.5 g of magnesium ribbon is reacted with an excess of 1 mol/dm³ hydrochloric acid. The volume of hydrogen p…

Redox / Oxidation and Reduction

Colour changes are often observed when redox reactions occur. Which colour change is due to the reduction of the named r…

Acids / Reactions of Dilute Acids

Dilute sulfuric acid is added to separate samples of solid substances. Which row is correct?…

Salts / Preparation of Salts

Given a supply of lead carbonate, copper carbonate, dilute nitric acid and aqueous sodium hydroxide, how many different …

Salts / Preparation of Salts

A salt can be prepared by adding an excess of solid X to an aqueous solution of Y. A solution and some solid X remain. T…

Ammonia / Reactions of Ammonium Salts

Ammonia can be displaced from its salts. Which equation is correct?…

Periodic Table / Groups and Reactivity

The diagram shows part of the Periodic Table. Which two elements would react together most vigorously?…

Group VII / Halogen Displacement

In the equation shown, X and Y represent elements in Group VII of the Periodic Table. X₂ + 2KY → Y₂ + 2KX Which pair of …

Transition Elements / Properties

Which statement about transition elements is correct?…

Metals / Reactivity Series and Extraction

X is a metal. It occurs naturally as an element and sometimes in ores containing its oxide. X can be used to make a chlo…

Redox / Redox Reactions

The equations show reactions that take place in the blast furnace. 1 Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g) 2 C(s) + O₂(g)…

Metals / Alloys

Which alloy of iron is used in surgical instruments?…

Air / Catalytic Converters

In the catalytic converter of a car, what type of chemical reaction takes place to change the harmful exhaust gases, car…

Air and Atmosphere / Carbon Dioxide

Which process removes carbon dioxide from the atmosphere?…

Separation Techniques / Immiscible Liquids

A liquid mixture contains a hydrocarbon and water. The boiling points and densities of the hydrocarbon and of water are …

Chemical Bonding / Covalent Bonds

How many electrons are involved in the bonding between carbon and one of the oxygens in carbon dioxide, CO₂, and between…

Acids and Bases / Ions in Solution

Each of the following solutions has a concentration of 1 mol/dm³. Which solution contains the greatest number of ions in…

Organic Chemistry / Alkenes

What is the general formula for the alkenes homologous series?…

Organic Chemistry / Alkanes

A compound has the formula C₄H₁₀. Which statement about this compound is correct?…

Organic Chemistry / Cracking

Which statements about the cracking of hydrocarbons are correct? 1 Cracking involves breaking down hydrocarbon molecules…

Organic Chemistry / Reactions of Ethene

Which row shows the products of the complete combustion of ethene and the products of the reaction of ethene with chlori…

Organic Chemistry / Alkenes and Hydration

Compound Z • has the empirical formula CH₂ • has an Mᵣ of 56 • reacts with steam to form two alcohols that have differen…

Organic Chemistry / Reaction Pathways

The flow chart shows some of the reactions of organic compounds. Which row describes the types of reactions involved?…

Polymers / Condensation Polymerisation

Two compounds, X and Y, react together to form the polymer nylon. X is H₂N-(CH₂)₆-NH₂ and Y is HOOC-(CH₂)₄-COOH. What is…