2022 DMSS Chem Prelims P2

[Turn over DAMAI SECONDARY SCHOOL Preliminary Examination 2022 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Paper 2 Secondary 4 Express Setter: Ms See Pei Zhen No Additional Materials are required. 6092/02 23 August 2022 1 hour 45 minutes 80 marks READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions in the spaces provided. Section B Answer all three questions. The last question is in the form either / or. Answer all questions in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is provided on page 20. The use of an approved scientific calculator is expected, where appropriate. For Examiner’s Use Section A / 50 Section B / 30 Total / 80 This document consists of 20 printed pages.

2 Section A Answer all questions in this section in the spaces provided. A1 (a) Select elements from the list to answer the following questions. You may use each element once, more than once or not at all. aluminium astatine chlorine helium manganese neon phosphorus rubidium strontium tin (i) Which of the elements is a diatomic gas at room temperature? ………………………………………………………………………………….. [1] (ii) Which of the elements forms an oxide which reacts with an acid and an alkali separately? ………………………………………………………………………………….. [1] (iii) Which of the elements forms a stable ion of type X2+ ? ………………………………………………………………………………….. [1] (iv) Which of the elements changes the colour of aqueous potassium iodide from colourless to brown? ………………………………………………………………………………….. [1] (v) Which of the elements can have possible oxidation states of +2 and +4? ………………………………………………………………………………….. [1]

3 [Turn over (b) One isotope of rubidium is rubidium-87. State the number of sub-atomic particles found in an ion of rubidium-87. sub-atomic particle number of particles protons neutrons electrons [2] [Total: 7]

4 A2 Fragrance of perfumes spreading around the room is an example of diffusion. (a) Define diffusion. …………………………………………………………………………………………….. …………………………………………………………………………………………. [1] (b) Explain, using kinetic particle theory, why gases diffuse faster than solids and liquids. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] (c) When colourless phosphine, PH3, and colourless hydrogen iodide, HI, come into contact, a brown solid is formed. PH3 (g) + HI (g) → PH4I (s) brown solid The following apparatus can be used to compare the rate of diffusion of the two gases, phosphine and hydrogen iodide. Predict at which position, A, B or C, the brown solid will form. Explain your answer. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [3] [Total: 6] cotton wool soaked in water and calcium phosphide gives off PH3 (g) cotton wool soaked in concentrated hydroiodic acid gives off HI (g) A B C

5 [Turn over A3 Table 3.1 shows some information about planet Mars. Table 3.1 current surface temperature/ºC –143 to 35 composition of planet 93 % iron 7 % nickel composition of atmosphere 95.3 % carbon dioxide 2.7 % nitrogen 1.6 % argon 0.13 % oxygen 0.07 % carbon monoxide (a) Using Table 3.1, state two differences between the compositions of atmosphere on Mars and on Earth. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] (b) Due to the presence of underground ice and soil nutrients that are suitable for plant growth, astronomers believe that there is a potential for plant life to appear on Mars in future. The appearance of plant life could potentially change the percentages of oxygen and carbon dioxide in the atmosphere of Mars. How would you expect the percentages of these two gases to change? Give a reason for your answer. Include a suitable equation in your explanation. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [3] [Total: 5]

6 A4 Sulfamic acid, SO3NH3, is a strong acid used to remove limescale from kettles. (a) Define strong acid. …………………………………………………………………………………………….. ……………………………………………………………………………………….....[1] (b) Aqueous sulfamic acid reacts with sodium hydroxide solution to form aqueous sodium sulfamate, NaSO3NH2. (i) Write an equation for this reaction. .........…………………………………………………………………………….[1] (ii) Limescale contains calcium carbonate. Describe, with the aid of an equation, how aqueous sulfamic acid reacts with calcium carbonate. ….………………………………………………………………………………….. ....……………………………………………………………………………….….. ………………………………………………………………………………….. [2] (c) When sulfamic acid crystals is dissolved in water and heated, sulfuric acid and a colourless gas is formed. Suggest the identity of the colourless gas. Describe a test, and the positive observation, for the gas. identity of gas ..………………………………………………………………………….. test and observation ...…………………………………………………………………. ..………………………………………………………………………….................... [2] [Total: 6]

7 [Turn over A5 Zirconium is a metallic element found in Period 5 of the Periodic Table. Due to its high melting point, zirconium is used to made containers for fuel rods in nuclear reactors. (a) Use ideas about bonding and structure to explain why zirconium has a high melting point. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] (b) In the event of a nuclear accident, water can come into contact with the very hot zirconium container. Above 1230 ºC, zirconium reacts with steam to form zirconium(IV) oxide and a gas. (i) Write an equation, with state symbols, for the reaction. …………………………………………………………………………………. [2] (ii) Explain why the reaction in (b)(i) inside the reactor makes nuclear accidents more dangerous. …………………………………………………………………………………….. .…………………………………………………………………………………. [2] [Total: 6]

8 A6 Fig. 6.1 shows some information about the Haber process for making ammonia. Fig. 6.1 (a) A finely divided catalyst is used in the Haber process. (i) Name the catalyst used. ………………………………………………………….………………………. [1] (ii) Explain how a finely divided catalyst speeds up the rate of a reaction. ……………………………………………………………….…………………….. ……………………………………………………………….…………………….. ………………………………………………………….………………………. [2] (b) Explain why the percentage yield of ammonia from the Haber process is typically low. Include a suitable equation in your explanation. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] [Total: 5] pump reactor containing finely divided catalyst cooler unreacted nitrogen and hydrogen IN nitrogen and hydrogen OUT liquid ammonia

9 [Turn over A7 Electrolysis is carried out on two substances using platinum electrodes. (a) Complete Table 7.1. Table 7.1 anode (+) cathode (–) name of product observation name of product observation molten magnesium chloride concentrated magnesium chloride solution [4] (b) Universal indicator is added to the electrolysis set-up of dilute sodium chloride. Suggest the col