O Levels G3 Combined Chemistry Paper 1 mock Name 1 / 20 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 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 3 / 20 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, 4 / 20 An unknown substance X starts melting at –180 °C and finishes melting at –160 °C. What is substance X likely to be? a compound a mixture an element insufficient data to determine Pure compounds and elements will have a fixed melting point. Only mixtures melt over a range 5 / 20 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 6 / 20 The flowchart shows some reactions of a compound T. What could compound T be? aluminium carbonate ammonium nitrate calcium nitrate zinc carbonate Ammonium salt + Strong Alkali --> ammonia gas + water + salt test for nitrate: add sodium hydroxide solution to the sample, followed by aluminum foil, and gently heat the mixture. If nitrate ions are present, they will be reduced to ammonia gas, which can be detected by its pungent smell or by its ability to turn damp red litmus paper blue. 7 / 20 Heavy water is made up of 2 deuterium( Hydrogen atoms with mass number 2) atoms and 1 oxygen atom. Which properties are true about heavy water? 1 Its boiling point is higher than 100 °C. 2. It reacts with sodium to form sodium hydroxide and hydrogen gas. 3 It can act as a solvent for sodium chloride. 1 only 2 and 3 only 1, 2 and 3 none of the above Heavy water has a higher molar mass as compared to normal water, and the boiling point will be slightly higher. Howeve,r most of the chemical properties will be similar. 8 / 20 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. 9 / 20 Ammonia and excess carbon dioxide can react to form urea and water in a reaction. 2NH3 + CO2 → CON2H4 + H2O The percentage yield of this reaction is 80 %. What is the mass of ammonia required for this reaction to obtain 60.0 g of urea? [Mr: NH3, 17; CO2, 44; CON2H4, 60; H2O, 18] 10.6 g 27.2 g 34.0 g 42.5 g Molar mass of urea = 60g --> 1 mole 100/80 x 1 = 1.25 mole of urea mole of ammonia = 1.25 x 2 = 2.5 mole mass of ammonia = 2.5 x 17g = 42.5g 10 / 20 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 11 / 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 12 / 20 When excess aluminium oxide, Al2O3 was added to a portion of dilute sodium hydroxide. Which of the following correctly describes the pH change and the explanation? A B C D Aluminium oxide is amphoteric and neutralises the sodium hydroxide. Thus the pH decrease 13 / 20 Which equations below represent redox reactions? 1. H+ + OH− → H2O 2. MnO4− + 8H+ + 5e− → Mn2+ + 4H2O 3. Cl2 + 2Br −→ Br2 + 2Cl − 1 only 3 only 1 and 2 only 2 and 3 only neutralisation ( not redox) redox redox 14 / 20 On adding 50 g of impure limestone, CaCO3 (Mr = 100), to excess hydrochloric acid, 6.0 dm3 of CO2 was evolved at room temperature and pressure. What is the percentage purity of the limestone? 25% 50% 75% 100% CaCO3 + 2HCl --> CaCl2 + CO2 + H2O for CO2: 24dm3 --> 1 mole 6 dm3 --> 0.25 mole mole ratio of CO2 : CaCO3 1 : 1 0.25 : 0.25 Molar Mass of CaCO3 = 100g 0.25 mole --> 25g Therefore, % purity = (25/50) x 100% = 50 % 15 / 20 Calcium nitrate crystals contain water of crystallisation. Its formula may be written as Ca(NO3)2●nH2O. When a 7.00 g sample of hydrated calcium nitrate is heated to remove all water, 4.90 g of anhydrous calcium nitrate remains after heating. What is the value of n? 1 2 3 4 7 g - 4.9 g = 2.1g of water 1 mole water --> 18g 2.1 g --> 0.11667 mole 1 mole Calcium nitrate --> 164g 4.9g --> 0.029878 mole ratio 0.029878 : 0.11667 1 : 4 16 / 20 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 17 / 20 Oxygen was prepared and collected using the apparatus as shown in the diagram below. The first tube of gas collected was discarded as it was contaminated. Which contaminant was in the gas? hydrogen hydrogen peroxide manganese(IV) oxide nitrogen There would be air in the test tube and tubing. Thus the main contaminant would be nitrogen gas. 18 / 20 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. 19 / 20 When a 10 cm3 sample of a gaseous hydrocarbon was completely burnt in 35 cm3 of oxygen, the total volume of the products formed was 50 cm3. Which equation represents the combustion of the hydrocarbon? CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(g) C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g) 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g) Since all the reactants and products are gases, we can use the ratio of volume directly without converting to moles. 10: 35 : 50 2 : 7 : 10 ratio of hydrocarbon is 2, ratio of oxygen is 7 and ratio of the sum of products is 10. Only D satisfy this ratio 20 / 20 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. Your score isThe average score is 85% 0% Restart quiz
