Question 1 of 8
A curated set of real ZIMSEC past paper questions with answers and explanations. The full question bank is in the Danho app.
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Which one is an example of a change of state?
Which gas has the fastest rate of diffusion?
The diagram shows a chromatogram obtained using solutions of four single dyes.
Which is the best way to test for the purity of propanoic acid?
The diagram shows ammonium chloride being heated.
The diagram shows a chromatogram obtained using solutions of three single dyes (blue, green and red) and four other solutions (A, B, C and D).
Which process involves a change of state?
When liquid water changes into steam, the molecules
The diagram shows a chromatogram of the dyes present in five different inks.
The structural formula of butanedioic acid is shown.
Which structure has an ester bond?
The structure of a compound is shown.
Which structure represents a soap molecule resulting from the hydrolysis of fat with aqueous sodium hydroxide?
The graph shows a cooling curve of a substance, P.
Which change of state represents sublimation?
An amino acid has an R value of 0.75.
Which method is not suitable for separating a mixture of sand and water?
An example of a solid with a giant molecular structure is
Which compound is an alkane?
The structural formula of butanol is shown.
An investigation to identify the ink used to make a fake one hundred dollar note using paper chromatography was carried out. The chromatogram shown was obtained.
Which pair correctly describes the structure of an atom?
Which gas has the smallest rate of diffusion?
Which diagram correctly represents a sulphide ion, S?
The table shows information about the subatomic particles of two species, X and Y.
Which gas has the smallest rate of diffusion?
An ion of an element X is represented as follows, with W above and to the left of the symbol, Y above and to the right, and Z below and to the left.
Fig. 1 shows structures of four atoms/ions, A, B, C and D, drawn as nucleus-and-shell diagrams. Structures A and D have the same number of protons but different numbers of neutrons. Which two structures together represent a pair of isotopes?
In Fig. 1, atom A forms a covalent compound with hydrogen, shown by a dot-and-cross diagram in which A shares one electron pair with each of four hydrogen atoms. What is the name of this compound?
Methane (CH4) is the covalent compound formed when atom A in Fig. 1 bonds with four hydrogen atoms. Which of the following statements about methane is correct?
Which of the following Period 3 oxides is amphoteric, reacting with both acids and bases?
In an experiment, 2.4 g of magnesium (Mr = 24) reacts completely with a sample of black solid copper(II) oxide (Mr = 80), according to Mg + CuO -> MgO + Cu. What mass of copper(II) oxide reacted?
Copper metal is heated strongly in oxygen to form a black solid, B. What is B?
Write the ionic equation, including state symbols, for the reaction between barium ions and sulfate ions to form the white precipitate barium sulfate.
Molten lead(II) bromide is electrolysed using inert graphite electrodes. Which equation represents the reaction that occurs at the cathode?
Aqueous copper(II) sulfate is electrolysed using copper electrodes. What happens at the anode?
Chlorine-35, ³⁵Cl, has atomic (proton) number 17. State the number of neutrons in one atom of chlorine-35.
Which statement correctly describes a difference between a chlorine atom, Cl, and a chloride ion, Cl⁻?
Carbon tetrachloride, CCl4, is a liquid at room temperature while calcium chloride, CaCl2, is a solid. This is because...
Chlorine gas is bubbled through sodium bromide solution: Cl2 + 2NaBr → Br2 + 2NaCl. What type of reaction is this?
A student added black copper(II) oxide powder to nitric acid, forming a blue solution P containing copper(II) ions. Which other substance is present in solution P?
Write a balanced chemical equation, with state symbols, for the reaction between zinc granules and copper(II) sulfate solution.
In the Contact process for manufacturing sulfuric acid, Fig.5's flow diagram shows sulfur and dry air entering box A; the process proceeds A -> B -> C, with oxygen also fed into C; C -> D, with water entering D and concentrated sulfuric acid leaving D; D -> E, with waste gases leaving E. In which box is sulfur dioxide oxidised to sulfur trioxide (the catalytic converter)?
An element X has the electron configuration 2, 8, 3. In which period of the periodic table is X located?
An element X has the electron configuration 2, 8, 3. State, in one word, whether X is a metal or a non-metal.
Which of the following correctly defines the term diffusion?
Cotton wool soaked in concentrated ammonia is placed at one end of a glass tube, and cotton wool soaked in concentrated hydrochloric acid is placed at the other end. White fumes of ammonium chloride form off-centre in the tube, closer to the hydrochloric acid end. This happens because...
Element E has an electron arrangement of 2,8,7 across its three shells. What is the number of protons in atom E?
Element D has an electron arrangement of 2,8,2 across its three shells, and exists as a solid metal. What type of bonding exists between particles of D in its elemental form?
A burette containing sodium hydroxide solution, NaOH(aq), is clamped above a conical flask containing dilute sulfuric acid, H2SO4(aq), with 2-3 drops of a solution Y added to the acid before the NaOH is run in from the burette. Name the analytical technique being carried out.
In a titration where sodium hydroxide solution, NaOH(aq), is added from a burette into a conical flask containing dilute sulfuric acid, H2SO4(aq), with 2-3 drops of a solution Y added to the acid beforehand, what is the role of solution Y?
A mixture of sand and salt solution is to be separated so that the sand is left behind as a residue while the salt solution passes through. Name the separation method used.
Sulphuric acid is manufactured by the Contact process. Sulphur dioxide gas escapes as one pollutant from the process, and CaCO3 is used to minimise it. Name the second pollutant produced, an acidic mist that escapes when sulphur dioxide is further oxidised in the converter.
An ion X has 8 protons, 8 neutrons and a charge of 2-. An ion Y has 13 protons, 14 neutrons and a charge of 3+. State the formula of the compound formed when X and Y combine.
A pure substance is heated steadily from a solid. On its heating curve, B-C is a flat plateau (melting) and D-E is a later flat plateau (boiling), with the temperature rising continuously in between, over region C-D, and rising again after E. In region C-D, the substance is