MEYNAA SCHOOL Noonu – Holhudhoo UNIT TEST – 1 - SEMESTER I – 2020 Candidate Name: ………………………………………. Index No.: …………………. Grade: 10A Subject: Chemistry Marks: 40 Duration: 45min Section - A 1. The formulae of some ions are shown. Which formula is not correct? A) Al3 (SO4)2 B) K3PO4 C) Mg (NO3)2 D) TiCl4 2. In which row are the oxides correctly identified? 3. When dilute sulfuric acid is added to solid X, a colourless solution is formed and a gas is produced. The gas turns lime water into milky. What is X? A) Copper (II) oxide B) Sodium oxide C) Copper (II) carbonate D) Sodium carbonate 1 4. A few drops of methyl orange are added to a reaction mixture. During the reaction, a gas is produced and the methyl orange turns from red to orange. What are the reactants? A) aqueous sodium hydroxide and ammonium chloride B) aqueous sodium hydroxide and calcium carbonate C) dilute hydrochloric acid and magnesium D) dilute hydrochloric acid and aqueous sodium hydroxide 5. Some general rules for the solubility of salts in water are listed. • Carbonates are insoluble (except ammonium carbonate, potassium carbonate and sodium carbonate). • Chlorides are soluble (except lead(II) chloride and silver chloride). • Nitrates are soluble. • Sulfates are soluble (except barium sulfate, calcium sulfate and lead(II) sulfate). Which substances produce an insoluble salt when aqueous solutions of them are mixed? A) barium chloride and magnesium nitrate B) calcium chloride and ammonium nitrate C) silver nitrate and zinc chloride D) sodium carbonate and potassium sulfate 6. Argon is a noble gas used to fill light bulbs. What is the approximate percentage of argon in air? A) 1% B) 20% C) 79% D) 99% 7. Which statements about sulfur dioxide pollution are correct? 1. It increases the pH of rivers. 2. It damages limestone buildings. 3. It causes respiratory problems. A) 1 only B) 2 only C) 1 and 3 D) 2 and 3 8. In the carbon cycle, which two processes add carbon dioxide to the atmosphere? A) combustion and carbonate formation B) combustion and photosynthesis C) combustion and respiration D) respiration and photosynthesis 2 9. What is the molecular weight (Mr) of Mg (OH)2? A) 21 B) 30 C) 42 D) 58 10. The positions of two elements, P (group 7) and Q (group 1), in the Periodic Table are shown. P and Q react together to form a compound. What is the formula of the compound? A) QP B) Q2P C) Q7P D) QP7 Section B 11. Solid N and solid O were analysed. Solid N was ammonium sulfate. Tests were done on each solid. Tests on solid N Complete the expected observations. (a) Describe the appearance of solid N. ..............................................................................................................................................[1] Solid N was dissolved in distilled water to form solution N. Solution N was divided into two portions in two test‑tubes. (b) Dilute nitric acid and aqueous barium nitrate were added to the first portion of solution N. observations ......................................................................................................................... [2] 3 (c) Aqueous sodium hydroxide was added to the second portion of solution N. The mixture was heated and the gas produced was tested. observations …………................................................................................................................................ …………............................................................................................................................................... [2] (d) Name the gas produced in (c). ............................................................................................................................................... [1] Tests on solid O Some of the tests and observations are shown. Tests on solid O The appearance of solid O was studied. Observations white crystals Distilled water was added to some of solid O to form solution O. Solution O was divided into two equal portions in two test‑tubes. Test 1 An excess of aqueous sodium hydroxide was No reaction added to the first portion of solution O. Test 2 Dilute nitric acid and aqueous silver nitrate were White precipitate added to the second portion of solution O. Test 3 A flame test was done on the rest of solid O. Lilac colour (e) What conclusion can you draw about the identity of solid O from test 1? ............................................................................................................................................... [1] (f) Identify solid O. ............................................................................................................................................... [2] [Total: 9] 4 12. (a) All sodium salts are soluble in water. All nitrates are soluble in water. Barium carbonate is insoluble in water. Describe how you would make a pure, dry sample of barium carbonate by precipitation. Include: • the names of the starting materials • full practical details • a chemical equation. ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ............................................................................................................................................... [5] (b) When the hydrated copper(II) nitrate crystals are heated, steam is produced. When the steam condenses on a cool surface, it turns into a colourless liquid. Anhydrous cobalt(II) chloride is used to show that the colourless liquid contains water. How does the colour of the anhydrous cobalt(II) chloride change? from ............................................................... to ................................................................ [2] (c) How would the student test to determine if the water produced in (b)(iii) is pure? ........................................................................................................................................ [1] [Total: 8] 5 13. Air is a mixture. Nitrogen and oxygen are the two most common gases in air. (i) What is meant by the term mixture? ................................................................................................................................................... ..............................................................................................................................................[1] (ii) State the percentage of oxygen, to the nearest whole number, in clean dry air. ........................................................................................................................................ [1] (iii) Describe the steps in the industrial process which enables nitrogen and oxygen to be separated from clean dry air. Use scientific terms in your answer. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ........................................................................................................................................ [3] (iv) Which physical property of nitrogen and oxygen allows them to be separated? ........................................................................................................................................ [1] [Total: 6] 14. Ammonia is an important chemical. (a) Ammonia is a base. (i) In chemistry, what is meant by the term base? ..................................................................................................................................................................... ............................................................................................................................................................... [1] 6 (ii) Write a word equation to show ammonia behaving as a base. ......................................................................................................................................................... ....................................................................................................................................................[2] (b) Ammonia reacts with chlorine. The chemical equation is shown. 2NH3 (g) + 3Cl2 (g) → N2 (g) + 6HCl (g) (i) Calculate the volume of chlorine, measured at room temperature and pressure, needed to react completely with 0.68 g of ammonia. volume of chlorine = .............................. cm3 [3] [Total: 7] 7
