10.1. Water
A subsection of Chemistry, 0620, through 10. Chemistry of the environment
Listing 10 of 242 questions
The list shows some gases in a sample of water. Choose from the list the gas that is essential for aquatic life. Draw a circle around your chosen answer. argon hydrogen nitrogen oxygen Polluted water contains harmful substances. Link each harmful substance on the left to the correct effect on the right. One has been done for you. harmful substance effect are toxic to aquatic organisms contains harmful microbes which cause disease harm aquatic life when eaten lead to deoxygenation of water plastics sewage nitrates metal compounds such as mercury(chloride Table 3.1 shows the masses of ions, in mg, present in a 1000 cm3 sample of polluted water. Table 3.1 name of ion formula of ion mass of ion in 1000 cm3 of polluted water / mg bromide Br – 0.1 calcium Ca2+ 2.0 chloride Cl – 3.5 hydrogencarbonate HCO3 – 12.0 magnesium Mg2+ 0.8 mercury Hg2+ 0.3 nitrate NO3 – 0.4 phosphate PO4 3– 2.0 potassium K+ 6.4 silicate SiO3 2– 4.0 sodium Na+ 10.2 SO4 2– 0.5 tin Sn2+ 0.2 Answer these questions using the information from Table 3.1. Name the positive ion that has the lowest concentration. State the name of the SO4 2– ion. Calculate the mass of potassium ions in 125 cm3 of polluted water. mass = mg Name two substances used in the treatment of the domestic water supply. For each substance give a reason for its use. substance 1 reason substance 2 reason Complete the symbol equation for the reaction of silicon(chloride, SiCl 4, with water. SiCl 4 + H2O → SiO2 + HCl
0620_w24_qp_33
THEORY
2024
Paper 3, Variant 3
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The diagram below shows part of the Water Cycle. sea H2OH2OSun cloud H2Oland rain State the name of each of the following changes of state. H2O→ H2Oname H2O→ H2Oname Which one of the above changes of state is exothermic? Explain your choice. The rain drains into rivers and then into reservoirs. Describe how water is treated before it enters the water supply. Explain how acid rain is formed. Fish live in water which is neutral (neither acidic nor alkaline). Acid rain decreases the pH of water in lakes and rivers. Both of the bases, calcium oxide and calcium carbonate, can neutralise this acid and increase the pH. Explain why calcium carbonate is a better choice.
0620_s12_qp_31
THEORY
2012
Paper 3, Variant 1
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Questions Discovered
242