O Level Chemistry 5070 Paper 12, Oct/Nov 2024

Helium gas and argon gas are mixed in a closed container at room temperature and pressure (r.t.p.). What happens when the two gases are in the container? A Argon and helium atoms become evenly mixed throughout the container even though they have different masses. B Argon and helium atoms both move towards the bottom of the container. The argon atoms settle more quickly because they are larger and heavier. C Argon and helium atoms both move towards the bottom of the container. The helium atoms settle more quickly because they are smaller and lighter. D Argon atoms move to the bottom of the container because they are heavier. Helium atoms move to the top of the container because they are lighter.

Substance X has a simple molecular structure and substance Y has a giant covalent structure. Which row is correct?

The diagram shows an atom of element Z. Which symbol for element Z is correct? A ${}_{28}^{15}\text{Z}$ B ${}_{13}^{26}\text{Z}$ C ${}_{13}^{28}\text{Z}$ D ${}_{15}^{28}\text{Z}$

A sample of element Q contains two isotopes. The diagram shows the relative abundances and relative masses of the two isotopes. What is the relative atomic mass, $A_r$, of this sample of Q? A 21.0 B 21.2 C 21.5 D 21.7

Which statement about electrical conductivity is correct? A Covalent compounds, such as glucose, conduct when molten or dissolved in water. B Dilute acids, such as sulfuric acid, conduct because all the ions are free to move. C Ionic compounds, such as sodium chloride, conduct due to movement of electrons. D Metals, such as copper, conduct due to movement of positive ions.

Which substance is not malleable and conducts electricity by the movement of electrons through a lattice of atoms? A aqueous sodium chloride B gold C graphite D solid sodium chloride

What is the relative molecular mass, $M_r$, of ethene? A the average mass of the isotopes of C and H compared to $\frac{1}{12}$ of the mass of an atom of ${}^{12}\text{C}$ B the atomic numbers of the isotopes of C and H compared to $\frac{1}{12}$ of the mass of an atom of ${}^{12}\text{C}$ C twice the $A_r$ of C plus four times the $A_r$ of H D twice the $A_r$ of C plus six times the $A_r$ of H

What is the relative molecular mass, $M_r$, of ${\text{N}}_2\text{O}$? A 22 B 30 C 44 D 46

Which contains the greatest mass of oxygen? A $0.2\text{ mol}$ of aluminium nitrate, ${\text{Al(NO}}_3{)}_3$ B $0.3\text{ mol}$ of potassium sulfate, ${\text{K}}_2{\text{SO}}_4$ C $0.4\text{ mol}$ of sodium nitrate, ${\text{NaNO}}_3$ D $0.5\text{ mol}$ of magnesium carbonate, ${\text{MgCO}}_3$

Compound Z contains carbon, hydrogen and oxygen only. Compound Z contains 48.65% carbon and 8.11% hydrogen by mass. What is the empirical formula of Z? A ${\text{C}}_2{\text{H}}_4\text{O}$ B ${\text{C}}_3{\text{H}}_6{\text{O}}_2$ C ${\text{C}}_4{\text{H}}_8{\text{O}}_3$ D ${\text{C}}_8{\text{H}}_{16}{\text{O}}_5$

Which fertiliser contains the highest percentage by mass of nitrogen? [$M_r$: ${\text{NH}}_4{\text{NO}}_3$, 80; $({\text{NH}}_4{)}_3{\text{PO}}_4$, 149; $({\text{NH}}_4{)}_2{\text{SO}}_4$, 132; $({\text{NH}}_2{)}_2\text{CO}$, 60] A ${\text{NH}}_4{\text{NO}}_3$ B $({\text{NH}}_4{)}_3{\text{PO}}_4$ C $({\text{NH}}_4{)}_2{\text{SO}}_4$ D $({\text{NH}}_2{)}_2\text{CO}$

An electrolytic cell is shown. Which statement is correct? A Electrons move from the cathode to the anode in the external circuit. B Hydrogen ions gain electrons at the anode. C In the electrolyte, positive ions move to the cathode and negative ions move to the anode. D The hydroxide ions in the electrolyte move to the cathode.

An aqueous mixture of copper(II) nitrate and silver nitrate is electrolysed with pure copper electrodes. Which ionic half-equation describes the change occurring at the anode? A $\text{Cu}\to {\text{Cu}}^{2+}+2{\text{e}}^{-}$ B ${\text{Cu}}^{2+}+2{\text{e}}^{-}\to \text{Cu}$ C $\text{Ag}\to {\text{Ag}}^{+}+{\text{e}}^{-}$ D ${\text{Ag}}^{+}+{\text{e}}^{-}\to \text{Ag}$

What is a disadvantage of using a hydrogen-oxygen fuel cell to power a car? A Gasoline / petrol is a non-renewable resource. B The hydrogen tank may split in an accident, leading to an explosion. C The product of the reaction between oxygen and hydrogen is toxic. D The oxygen is obtained from air.

When chemical reaction X takes place, thermal energy is given out. Which row is correct for this reaction?

Which statement about a physical change is correct? A A physical change is impossible to reverse. B In a physical change, the appearance of a substance may change. C New substances are formed in a physical change. D There is no energy released or taken in during a physical change.

Gas P decomposes to form gas Q. $$x\text{P}\to y\text{Q}$$ Two experiments are done to investigate the rate of reaction. The conditions are the same except that two different temperatures, $T_1$ and $T_2$, are used. The results are plotted on graphs, drawn to the same scale. Which row is correct?

Samples of nitrogen and hydrogen are reacted and allowed to reach equilibrium. The equation is shown. $${\text{N}}_2+3{\text{H}}_2\rightleftharpoons 2{\text{NH}}_3\mathrm{\Delta }H=-92\text{ kJ / mol}$$ The temperature is increased and a new equilibrium is established. Which statement about the new equilibrium is correct? A The amount of product increases. B The amount of product decreases. C The rate of the forward reaction is greater than the rate of the reverse reaction. D The rate of the forward reaction is less than the rate of the reverse reaction.

In the diagram, R represents one of the reactions in the Contact process. Which statement is correct? A Gas Z is ${\text{SO}}_2$. B In R, an iron catalyst speeds up the reaction. C In R, the pressure is approximately $200\text{ atm}$. D In R, the temperature is approximately $45{}^{\circ }\text{C}$.

Peroxodisulfate ions, ${\text{S}}_2{\text{O}}_8^{2-}$, react with iron(II) ions, ${\text{Fe}}^{2+}$. $${\text{S}}_2{\text{O}}_8^{2-}+2{\text{Fe}}^{2+}\to 2{\text{SO}}_4^{2-}+2{\text{Fe}}^{3+}$$ The only elements that are either oxidised or reduced in this reaction are sulfur and iron. Which row is correct?

Which solid reacts with dilute hydrochloric acid to produce a gas? A carbon B copper C magnesium oxide D sodium carbonate

Which $1{\text{ mol / dm}}^3$ aqueous solution has the highest pH? A hydrochloric acid B sodium chloride C sodium hydroxide D sulfuric acid

Oxide Q reacts with separate samples of dilute hydrochloric acid and aqueous potassium hydroxide. Both reactions produce a salt and water. Which statement is correct? A Q is an acidic oxide. B Q is an amphoteric oxide. C Q is a basic oxide. D Q is a non-metal oxide.

The table shows four methods used to prepare pure salts. Which row shows a method of making a pure sample of each named salt?

Which property determines the order of the elements in the Periodic Table? A the masses of their atoms B the number of electrons in the outer shell C the number of neutrons in the nucleus D the number of protons in the nucleus

Which statement explains why helium and neon are unreactive? A They are both gases at room temperature and pressure. B They both have eight electrons in their outer shell. C They both have equal numbers of protons and electrons in their atoms. D They both have all their occupied electron shells completely filled.

Substance X conducts electricity in the solid state. Substance X is malleable. Which statement is correct? A X conducts electricity by the movement of electrons between layers of negative ions. B X conducts electricity by the movement of positive ions through a giant lattice. C X has a giant lattice of positive ions in a 'sea' of delocalised electrons. D X has layers of atoms with delocalised electrons between the layers.

Aluminium and copper are good conductors of electricity. Why is aluminium used in overhead electrical cables instead of copper? A Aluminium is above copper in the reactivity series. B Aluminium is less dense than copper. C Copper does not have an oxide coating. D Copper reacts with water.

The oxide of Z is reduced by heating with carbon. What is Z? A aluminium B calcium C magnesium D zinc

A metal ore contains an oxide, MO. Metal M forms coloured compounds. When a piece of iron is placed into a solution containing aqueous ${\text{M}}^{2+}$ ions, M is displaced. Which row is correct?

Iron can be extracted from the ore hematite. What is the maximum mass of iron that is produced from $500\text{ kg}$ of hematite? [$A_r$: O, 16; Fe, 56] A $160\text{ kg}$ B $240\text{ kg}$ C $350\text{ kg}$ D $420\text{ kg}$

Which row describes an advantage and a disadvantage of fertilisers?

Which row about the adverse effects of air pollutants is correct?

How many different unbranched esters have the molecular formula ${\text{C}}_4{\text{H}}_8{\text{O}}_2$? A 1 B 2 C 3 D 4

Petroleum is separated in a fractionating column. Which statements are correct? 1 The compounds at the top of the column are more volatile and have lower boiling points. 2 The compounds at the bottom of the column are more viscous. 3 The chain length of the molecules at the bottom of the column are shorter than those at the top. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Which statement about hydrocarbons is correct? A Alkenes are unsaturated which means that they are less soluble in water than alkanes. B Alkenes contain a higher percentage by mass of carbon than alkanes. C Cracking large alkanes produces only smaller alkanes and hydrogen. D The presence of a double bond in an alkene means that $1\text{ mol}$ of alkene will react with exactly $80.0\text{ g}$ of bromine.

Two statements are shown. 1 When ethanol is made from glucose by fermentation, each glucose molecule produces two molecules of ethanol. 2 When ethanoic acid is made from ethanol, the ethanol acts as a reducing agent. Which description of these statements is correct? A Statements 1 and 2 are both true. B Statement 1 is true. Statement 2 is false. C Statement 1 is false. Statement 2 is true. D Statements 1 and 2 are both false.

In a titration, a $25.0{\text{ cm}}^3$ sample of $0.100{\text{ mol / dm}}^3$ sodium hydroxide is exactly neutralised by $16.2{\text{ cm}}^3$ of dilute sulfuric acid. The equation for the reaction is shown. $${\text{H}}_2{\text{SO}}_4+2\text{NaOH}\to {\text{Na}}_2{\text{SO}}_4+2{\text{H}}_2\text{O}$$ What is the concentration of the dilute sulfuric acid? A $0.0648{\text{ mol / dm}}^3$ B $0.0772{\text{ mol / dm}}^3$ C $0.154{\text{ mol / dm}}^3$ D $0.309{\text{ mol / dm}}^3$

Three liquids, X, Y and Z, are tested and the results are shown.

What may be deduced about X, Y and Z from this information?

Compound Q is soluble in water. A solution of Q gives a white precipitate when dilute sulfuric acid is added. When Q is warmed with aqueous sodium hydroxide and aluminium foil, a gas is produced which turns damp red litmus paper blue. What is Q? A ammonium chloride B ammonium nitrate C barium chloride D barium nitrate