O Levels Combined Chemistry G3 O Levels G3 Combined Chemistry Paper 1 mock Name 1 / 20 1. Which element does not form a stable ion with the same electronic configuration as neon? Magnesium Fluorine Sodium Sulfur Sulfur is 2,8,6 so when it form an ion, it will be 2,8,8 which is the electron configuration of Argon 2 / 20 2. Aqueous hydrogen peroxide decomposes to form water and oxygen gas. Two experiments were carried out to measure the rate of production of oxygen from aqueous hydrogen peroxide. A B C D Experiment B has more starting reactant but lower concentration than A. Therefore, the curve will be less steep but finish higher. 3 / 20 3. Which statement is correct? 1.00 mol of zinc chloride contains 1.20 × 10^24 ions. 2.00 mol of sodium nitrate contains 1.20 × 10^24 ions. 24.0 dm3 of chlorine gas, measured at room temperature and pressure, contains 1.20 × 10^24 atoms. 48.0 dm3 of hydrogen gas, measured at room temperature and pressure, contains 1.20 × 10^24 atoms. 1 mole of any gas at rtp is 24 dm^3. therefore 24 dm^3 of chlorine gas has 1 mole of cl2 molecules which is 2 mole of atoms = 2 x 6 x10^23 = 1.2 x 10 ^24 4 / 20 4. How many of the following processes will lead to an increase in greenhouse gas emissions? 1 2 3 4 decomposition -> give out carbon dioxide fermentation -> give our carbon dioxide photosynthesis -> take in carbon dioxide polymerisation -> none, maybe water respiration -> give out carbon dioxide neutralisation -> only salt and water 5 / 20 5. An unknown solid Q has the following properties. •When aqueous sodium hydroxide is added until in excess to the solution, no visible reaction is observed. • When dilute acid is added to Q, effervescence of a colourless gas is observed. • Q dissolves in water to form a colourless solution. • Q is stable to heat. What is Q likely to be? ammonium carbonate copper(II) hydroxide sodium carbonate zinc carbonate • When aqueous sodium hydroxide is added in excess to sodium carbonate, no reaction takes place • When dilute acid is added to sodium carbonate, carbon dioxide is evolved. • Sodium carbonate is soluble in water and form a colourless solution. • sodium carbonate is stable to heat. 6 / 20 6. Which property of elements increases from left to right of Period 3 of the Periodic Table? number of outer shells metallic character tendency to get reduced melting points As you move from left to right across a period, the number of protons in the nucleus increases, which leads to a stronger attraction for electrons. This increased attraction makes it more difficult for an atom to lose electrons, 7 / 20 7. Which statement explains why sodium chloride, NaCl, has a lower melting point than magnesium oxide, MgO? Sodium chloride has a simple molecular structure while magnesium oxide has a giant ionic structure. Sodium is more reactive than magnesium. The attraction between Na+ and Cl− is weaker than that between Mg2+ and O2−. The particles in sodium chloride are more closely packed than in magnesium oxide. Both compounds are giant ionic structures. But the magnesium ion charge is 2+ while the sodium ion is 1+. Thus, the electrostatic forces holding the ions together are stronger in magnesium chloride 8 / 20 8. Hydrogen gas reacts with chlorine gas to form hydrogen chloride gas. H2(g) + Cl2(g) → 2HCl(g) What is the final volume of the gas mixture when 20 dm3 of hydrogen is reacted with 30 dm3 of chlorine gas at 100 C? 40 dm3 50 dm3 60 dm3 70 dm3 H2(g) + Cl2(g) → 2HCl(g) hydrogen gas is limiting reagent. Cl2 gas is excess by 10 dm3 Vol of HCl produced = 2 x 20 dm3 = 40 dm3 Final volume = 40 + 10 = 50 dm3 9 / 20 9. A warship had its hull plated in copper to protect its wooden hull from rotting. However, after 2 years at sea, it was found that the iron parts of the warship in contact with the copper plates were more corroded than normal. What is the best explanation for this observation? Copper acts as a catalyst to speed up corrosion. Copper reacts with the iron to increase corrosion. Iron displaces copper to form iron(III) oxide. Iron is more reactive and corrodes in place of copper. Iron is above copper in the reactivity series. Iron will readily give away electrons to copper. Thus, iron will ionize easily to react with the oxygen in the air to rust. 10 / 20 10. An element T forms an ion, T2+, which has an electronic arrangement 2.8.8. Which statement(s) concerning T is/are correct? I T is an alkali metal. II T forms a basic oxide with oxygen. III T is in Period 4 of the Periodic Table. I and II only I and III only II and III only I , II and III Since its ion's charge is 2+, it is in group 2 and called Alkali Earth metal not alkali metal. 2,8,8,2 is calcium which is in period 4 as its atom have 4 electron shells. Its oxide is basic. 11 / 20 11. In which chemical reaction does the named product have a higher relative molecular mass than the reactant? the formation of ethanol from glucose the formation of propene from octane the formation of carbon dioxide from butane the formation of dichloromethane from methane methane CH4 molar mass = 12 +4 = 16g dichloromethan CH2Cl2 molar mass = 12 +2 + 71 = 85g 12 / 20 12. A reaction takes place in two stages in the presence of a catalyst: Which ion is the catalyst in the reaction? Fe^2+ (aq) I^– (aq) SO4^2– (aq) S2O8^2– (aq) The catalyst must remain unchanged at the end of the reaction. 13 / 20 13. CH4, H2O and HCl are covalent compounds. Which atoms in these compounds do not use all their outer shell electrons in bonding? C and H C and O O and Cl Cl and C O has 6 valence electrons and only uses 2 for bonding Cl has 7 valence electrons and only uses 1 for bonding 14 / 20 14. An impure sample of calcium carbonate with a mass of 1.70 g was reacted with excess hydrochloric acid and 360 cm3 of carbon dioxide was collected at room temperature and pressure. What is the percentage purity of the calcium carbonate? 75% 88% 90% 98% CaCO3 + 2HCl --> CaCl2 + CO2 + H2O 1 mole --> 24000 cm3 360 cm3 --> 0.015 mole Ratio of CaCO3 : CO2 1:1 mole of CaCO3 = 0.015 mole molar mass of CaCO3 = 100g mass = 0.015 x 100 = 1.5g % purity = 1.5/1.7 x 100% = 88.2% 15 / 20 15. 50.0 cm3 of 0.10 mol/dm3 silver nitrate, AgNO3, is added to 150.0 cm3 of 0.05 mol/dm3 of sodium iodide, NaI, in a beaker. After the reaction, solid silver iodide is present in the beaker. What else is present in the mixture? Ag+, Na+, NO3- only Na+, I-, NO3- only Na+, I- only Na+, NO3- only AgNO3 + NaI --> NaNO3 + AgI 50.0 cm3 of 0.10 mol/dm3 silver nitrate, AgNO3 = 0.005 mole 150.0 cm3 of 0.05 mol/dm3 of sodium iodide, NaI, = 0.0075 mole Reactant ions left = Na+ and I - product ions = Na+ and NO3^- 16 / 20 16. The structure of brass is shown below. What is the purpose of adding zinc to copper? to make the packing of atoms more compact to strengthen the metallic bonds between copper atoms to prevent layers of copper atoms from sliding over each other easily to prevent the ‘sea of electrons’ from moving freely in the metal lattice Adding zinc atoms to copper disrupts the orderly arrangement, which prevents layers of copper atoms from sliding over each other easily. The effect is that the alloy is now harder and stronger than pure copper. 17 / 20 17. A paper chromatography experiment was carried out to determine the inks present in a mixture, and the results shown below were obtained. Which statement about the results is incorrect? Ink 4 is more soluble than ink 3 in the solvent used. Inks 1 and 2 contained more than one colour pigment. The ink mixture contained inks 1, 3 and 4. The Rf value of ink 3 in the solvent used is more than 0.5. The further the ink moved from the starting line, the more soluble it is in this solvent 18 / 20 18. Which of these Group 1 elements reacts most violently with water? caesium lithium potassium rubidium reactivity increases as it goes down the group. 19 / 20 19. Francium, Fr, is an element in the same group of the Periodic Table as lithium, sodium and potassium. Which statement about francium is likely to be correct? It forms a carbonate Fr2CO3. It forms coloured compounds. It reacts slowly with cold water. It is produced from the electrolysis of aqueous francium chloride. Use sodium or potassium as guide. Only extraction with electrolysis is true 20 / 20 20. Which of the following statements about a homologous series is correct? The melting and boiling point increases with increasing relative molecular mass. The members have similar physical properties. The members have the same molecular formula. The relative molecular masses of consecutive members differ by 12. The physical properties of members show a trend Your score isThe average score is 85% 0% Restart quiz
