Water. Question Paper 1. Chemistry (0620/0971) Cambridge International Examinations (CIE) Topic. Air and Water Sub-Topic. Water.

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1 For more awesome resources, visit us at Water Question Paper Level IGSE Subject hemistry (060/097) Exam oard ambridge International Examinations (IE) Topic ir and Water Sub-Topic Water ooklet Question Paper Time llowed: 0 minutes Score: /5 Percentage: /00 Grade oundaries: >85% 75% 68% 60% 5% 48% 40% % <5%

2 . Water must be purified before it is suitable for use in the home. Which processes are used to remove solid impurities and bacteria?. The diagram shows stages in the purification of water. Which stage uses chlorine? water at ph9 + bacteria + large solids + fine solids water at ph9 + bacteria + fine solids water at ph9 + bacteria pure water at ph7 water at ph7 + bacteria. When pink crystals of cobalt(ii) chloride are heated, steam is given off and the colour of the solid changes to blue. ol.6h O ol + 6H O What happens when water is added to the blue solid? colour changes to pink changes to pink remains blue remains blue tempe decreases increases decreases increases

3 4. Why is chlorination used in water treatment? to kill bacteria in the water to make the water neutral to make the water taste better to remove any salt in the water 5. Which pollutant, found in car exhaust fumes, does not come from the fuel? carbon monoxide hydrocarbons lead compounds nitrogen oxides 6. Which statements about water are correct? 4 Water is treated with chlorine to kill bacteria. Household water may contain salts in solution. Water is used in industry for cooling. Water for household use is filtered to remove soluble impurities., and and 4, and 4,, and 4

4 7. Water from a reservoir flows to the water works where purification processes takes place followed by process. What are purification processes and? 8. Separate samples of anhydrous and hydrated copper(ii) sulfate are heated. anhydrous copper(ii) sulfate hydrated copper(ii) sulfate heat heat Which shows the correct colour changes? anhydrous copper(ii) sulfate blue to white no change white to blue white to blue hydrated copper(ii) sulfate white to blue blue to white blue to white no change 4

5 9. Which processes are used in the treatment of water? filtration and chlorination filtration and reduction neutralisation and chlorination neutralisation and reduction 0. Solid copper(ii) sulfate can exist in two different forms, anhydrous and hydrated. One of these forms is blue and the other is white. The change between these two forms is reversible. blue form white form Which is the blue form and how is the change from the blue form to the white form brought about? blue form change to white form anhydrous add water anhydrous heat hydrated add water hydrated heat. Untreated water can spread diseases such as cholera. What can be added to drinking water to reduce the spread of such diseases? carbon monoxide chlorine nitrogen monoxide sulfur 5

6 . Some uses of water are listed. 4 for drinking in chemical reactions in swimming pools in washing For which uses is it necessary to chlorinate the water? and and and 4 and 4. Water for human use is treated by filtration then chlorination. Which uses do not need water of this quality? water for cooling in industry water for flushing toilets in the home water for drinking, and and only and only and only 4. In many countries river water is used for the washing of clothes. The same water is not considered to be safe for drinking. Why is it not safe for drinking? because river water contains dissolved salts because river water may contain harmful bacteria because river water may contain small particles of sand because river water may contain soap from washing clothes 6

7 5. Water is treated at a water works to make it fit to drink. What is present in the water when it leaves the waterworks? bacteria only bacteria and insoluble substances chlorine only chlorine and soluble substances 6. Water has been contaminated with sea-water. Which substances can be removed by chlorination and filtration? bacteria, sand and sodium chloride bacteria and sand only bacteria and sodium chloride only sand and sodium chloride only 7. The diagram shows a stage in the purification of dirty water. dirty water sand fine gravel pot with holes in bottom coarse gravel Which process does this apparatus show? chlorination condensation distillation filtration 7

8 8. Which method of purification would produce water most suitable for drinking? filtration muddy river water settlement chlorination filtration purified water filtration chlorination 9. The diagram shows some uses of water in the home. For which uses is it important for the water to have been treated? only only only, and 8

9 0 Some crystals of hydrated cobalt(ii) chloride are heated in a test-tube until no further change is observed. The test-tube is allowed to cool and a few drops of water are then added to the contents. Which colours are observed?. Which statements about water are correct? 4 Household water may contain salts in solution. Water for household use is filtered to remove soluble impurities. Water is treated with chlorine to kill bacteria. Water is used in industry for cooling.. If anhydrous copper(ii) sulfate is added to water, which colour change is observed? blue to pink blue to white pink to blue white to blue 9

10 . When pink crystals of cobalt(ii) chloride are heated, steam is given off and the colour of the solid changes to blue. ol.6h O ol + 6H O What happens when water is added to the blue solid? colour changes to pink changes to pink remains blue remains blue temperature decreases increases decreases increases 4. The diagram shows stages in producing drinking water. In which tank is chlorine added to the water? reservoir sedimentation tank filtration tank anti-bacterial treatment tank storage tank mains supply 5. Hydrated cobalt(ii) chloride decomposes on heating. The equation for the reaction is ol.6h O ol + 6H O The reaction is reversed by adding water. Which row describes the colour change and the type of reaction for the reverse reaction? colour change blue to pink blue to pink pink to blue pink to blue type of reaction endothermic exothermic endothermic exothermic 0