Angel International School - Manipay 2 nd Term Examination April, 2017 Chemistry

Transcription

1 Grade 09 Angel International School - Manipay 2 nd Term Examination April, 2017 Chemistry Duration: 2.30 Hours Index No:- Part -1 1) Select most suitable answers and underline them. 1) The diagram shows the result of dropping a purple crystal into water. Which processes take place in this experiment? 2) Chemists use symbols to identify each element. Recall which feature is true of these symbols. a) They use the first letter of the element name. b) They must use only capital letters. c) They contain one, two or three letters. d) They use only one or two letters. 3) The four pieces of apparatus shown below are used in chemical experiments. Which statement about the apparatus is correct? a) A burette measures the volume of liquid added in a titration. b) The measuring cylinder measures the mass of a substance used in an experiment. c) The pipette measures the volume of gas given off in a reaction. d) The thermometer measures the density of a solution. 4) The equation for the reaction between aqueous lead(ii) nitrate and aqueous potassium iodide is shown. Pb(NO 2 ) 2(aq) + 2KI (aq) PbI 2(s) + 2KNO 3(aq) colourless colourless yellow colourless Which method could be used to separate the products? a) Chromatography c) Distillation b) Crystallization d) Filtration 1

2 5) Alcohol and water are completely miscible. This means when mixed together they form only one liquid layer. Which method is used to separate alcohol from water? a) Crystallization b) Filtration c) fractional distillation d) Precipitation 6) The diagram shows the structure of an atom of element What is X? a) Boron b) Carbon c) Sodium d) Sulfur 7) The lead in a pencil is made of a mixture of graphite and clay. When the percentage of graphite is increased, the pencil slides across the paper more easily. Which statement explains this observation? a) Graphite has a high melting point. b) Graphite is a form of carbon. c) Graphite is a lubricant. d) Graphite is a non-metal. 8) An element has a melting point of 1084 C and a density of 8.93 g / cm3. It s oxide can be used as a catalyst. In which position in the Periodic Table is the element found? 9) The diagram shows a light bulb. Why is argon used instead of air in the light bulb? a) Argon is a good conductor of electricity. b) Argon is more reactive than air. c) The filament glows more brightly. d) The filament does not react with the argon. 10) Element X is in Group I of the Periodic Table. X reacts with element Y to form an ionic compound. Which equation shows the process that takes place when X forms ions? a) X + e X + b) X e X - c) X + e X - d) X e X + 11) Solid F is an element. Solid G is a compound. Neither solid conducts electricity but G conducts electricity when dissolved in water. These properties suggest that F is 1 and that G is 2 with 3 bonds. Which words correctly complete gaps 1, 2 and 3? 2

3 12) A compound contains one atom of calcium, two atoms of hydrogen and two atoms of oxygen. What is the correct chemical formula of the compound? a) CaO 2 H 2 c) H 2 CaO 2 b) HCaOOH d) Ca(OH) 2 13) Which substance will not conduct electricity? a) Aluminium b) Copper c) Plastic d) Steel 14) Which statements about alkalis are correct? 1. When reacted with an acid, the ph of the alkali increases. 2. When tested with litmus, the litmus turns blue. 3. When warmed with an ammonium salt, ammonia gas is given off. a) 1, 2 and 3 b) 1 and 2 only c) 1 and 3 only d) 2 and 3 only 15) Only two elements are liquid at 20 C. One of these elements is shiny and conducts electricity. This suggests that this element is a and therefore its oxide is Which words correctly complete gaps 1 and 2? 16) Which statement about the Periodic Table is correct? a) Elements in the same period have the same number of outer electrons. b) The elements on the left are usually gases. c) The most metallic elements are on the left. d) The relative atomic mass of the elements increases from right to left. 17) Why is argon gas used to fill electric lamps? a) It conducts electricity. b) It glows when heated. c) It is less dense than air. d) It is not reactive. 18) An element melts at 1455 C, has a density of 8.90 g / cm3 and forms a green chloride. Where in the Periodic Table is this element found? 19) The table shows properties of four metals. Which metal is the most suitable for aircraft construction? 3

4 20) Acid rain is formed when sulfur dioxide and oxides of nitrogen dissolve in rain water. Which problem is not caused by acid rain? a) breathing difficulties c) erosion of statues b) dying trees d) lowered ph of lakes 21) The letters X, Y and Z represent different atoms. What can be deduced from the proton numbers and nucleon numbers of X, Y and Z? a) X and Y are the same element. c) X has more protons than Y. b) X and Z are the same element. d) Z has more neutrons than Y. 22) The diagram shows some uses of water in the home. 23) For which uses is it important for the water to have been treated? a) 1 only b) 2 only c) 3 only d) 1, 2 and 3 24) Which diagram, A, B, C or D, best represents an alloy? 25) For which of the following can graphite be used? a) as an abrasive only b) as an abrasive and as an electrode 26) This table summarizes the physical properties of metals and non-metals. Recall the name of a substance that has high density and can be stretched into wire. a) A metal b) A non metal c) Plastic d) A fiber c) as an electrode and as a lubricant d) as a lubricant only 27) a) Decomposition reaction b) Composition reaction c) Precipitation reaction d) Redox reaction 4

5 28) Identify the atom in this diagram. a) Helium b) Lithium c) Boron d) beryllium 29) The diagram shows a method for separating a substance that contains X and Y. Which types of substance can be separated as shown? a) compounds b) elements c) Mixtures d) All of the above 30) Diagram 1 shows the paper chromatogram of substance X. Diagram 2 shows the cooling curve for substance Y. Which statement about X and Y is correct? a) Diagram 1 shows the paper chromatogram of substance X. b) X is a mixture and Y is a pure substance. c) X is a pure substance and Y is a mixture. d) X and Y are mixtures. 31) Equations P and Q represent two reactions which occur inside a blast furnace. P. Fe 2 O 3 + 3CO 2Fe + 3CO 2 Q.CaCO 3 CaO + CO 2 Which type of reactions are P and Q? 32) The diagram shows the circuit for electrolysing lead (II) bromide and sodium chloride to liberate the metal. In what form are these salts electrolysed for liberating the metal? 5

6 33) The diagrams show the arrangements of the electrons of four elements. Which two elements are metals? a) 1 and 2 b) 1 and 3 c) 2 and 4 d) 3 and 4 34) Use the Periodic Table to decide which element has all four of the properties shown. high melting point variable oxidation states good electrical conductivity forms coloured compounds a) cesium c) iodine b) cobalt d) strontium 35) The fractional distillation apparatus shown is being used to separate a mixture of two liquids. A Thermometer is missing from the apparatus. Where the bulb of the thermometer should be placed? 36) A particle contains 34 protons, 45 neutrons and 36 electrons. Which symbol is correct for this particle? 37) What happens when sodium chloride melts? a) Covalent bonds in a giant lattice are broken. b) Electrons are released from atoms. c) Electrostatic forces of attraction between ions are overcome. d) Molecules are separated into ions. 38) Concentrated aqueous sodium chloride is electrolyzed using inert electrodes. Which statement about this electrolysis is correct? a) Chloride ions travel through the solution to the negative electrode. b) Electrons travel through the solution to the sodium ions. c) Gases are given off at both electrodes. d) Sodium is formed at the negative electrode. 39) Some carbonate change colour when they are heated, copper carbonate changes from a) Blue to white b) Green to black c) Yellow to white d) Orange to yellow 6

7 40) In the circuit below, the lamp lights up. What could X be? a) a solution of ethanol in water b) a solution of sodium chloride in water c) liquid ethanol d) solid sodium chloride Part 2 1) Write the answers for all questions 1) Give the electronic configuration of the following atoms and ions : 1. Cu 2. Zn 3. Co Cr Fe 3+ (1X5=5) 2) Write the formula of these compounds: I. Silicon oxide II. Phosphorus chloride III. Ethane IV. Silver nitrate V. Magnesium nitrate (1X5=5) 3) Draw diagrams of the types of bonding in the following compounds: i. N 2 ii. CaCl 2 iii. H 2 O 2 iv. C 2 H 5 OH v. CO 2 (2X5= 10) 4) Aqueous chlorine reacts with aqueous potassium bromide. Cl 2 + 2KBr Br 2 + 2KCl i. Describe the colour change you would observe in this reaction.... ii. State the name of the salt formed in this reaction.... iii. Explain why aqueous bromine does not react with aqueous potassium chloride iv. The halogens exist as diatomic molecules. What is meant by the term diatomic?... (Total: 4) 7

8 5) The table shows the ions present in a sample of river water. I. Which ion with a charge of 2 + is present in the highest concentration?... II. 2- State the name of the ion with the formula SO III. Calculate the total mass of ions present in 1 dm3 of river water.... mg IV. Use your answer to part (iii) to calculate the total mass of ions in 50 cm3 of river water.... mg V. A student evaporated the sample of river water to leave a solid containing a number of different compounds. Use the information in the table to suggest the name of the compound present in the greatest amount.... (total 5) I. The table below shows some properties of some of the halogens. Deduce: The colour of astatine... The boiling point of bromine... The state of iodine at C.... [3] 8

9 1) The diagram shows part of the Periodic Table. Only some of the elements are shown. Answer the following questions using only the elements shown in the diagram. Each element may be used once, more than once or not at all. a) Which element has a giant covalent structure?... b) Which element has the highest relative atomic mass?... c) Which two elements are formed when molten aluminium oxide is electrolyzed?...and... [2] d) Which element in Group I reacts most rapidly with water?... e) Which element oxidizes in the presence of water to form rust?... f) Which element burns in oxygen to form water?... g) Rubidium reacts with oxygen to form rubidium oxide, Rb 2 O. Complete the symbol equation for this reaction....rb Rb 2 O [2] h) Lead compounds are atmospheric pollutants. State one adverse effect of lead compounds on health.... [Total: 10] 2) Lead (II) bromide is a white solid. Part of the structure of lead (II) bromide is shown below. A. Deduce the simplest formula for lead (II) bromide B. A student electrolyzed lead (II) bromide in a fume cupboard using the apparatus shown below. (i) Why is heat needed for this electrolysis? [2] 9

10 (ii) Suggest the name of a substance that could be used for the electrodes.... (iii) State the name of the products of electrolysis at: The anode,... The cathode.... C. Items can be electroplated with silver using the apparatus shown below. 1. On the diagram, which letter, A, B, C or D, is the cathode? What would you observe during the experiment at the: Positive electrode, Negative electrode?... [2] 4. The electrolyte used is aqueous silver cyanide, AgCN. Calculate the relative formula mass of silver cyanide. You must show all your working. [] (10 marks) A student carried out an investigation to coat a copper key with nickel. He followed these instructions. 1 Rub the copper key with sandpaper. 2 Set up the circuit as shown. 3 Switch on the circuit for ten minutes. 4 Remove the key, wash it and dry. 10

11 (a) Name the process used to coat the copper key with nickel. (b) Why was the key rubbed with sandpaper? [2] (c) Name a possible electrolyte that could be used. [2] (d) Give one expected observation during the ten minutes that the circuit was switched on. (e) Describe how the key would be washed and dried. [2] [Total: 8] ***** 11