0620_s22_qp_42
A paper of Chemistry, 0620
Questions:
6
Year:
2022
Paper:
4
Variant:
2

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1
The symbols of the elements of Period3 of the PeriodicTable are shown. Na Mg Al Si P S Cl Ar Answer the following questions about these elements. Each symbol may be used once, more than once or not at all. Write the symbol of the element which: forms a stable ion with a 2+ charge ������������������������������������������������������������������������������������� is the least reactive in the period ����������������������������������������������������������������������������������������� is used in water treatment ��������������������������������������������������������������������������������������������������� forms an oxide which is the main impurity in iron ore ���������������������������������������������������������� is an important component of fertilisers ������������������������������������������������������������������������������� is stored under oil ���������������������������������������������������������������������������������������������������������������� is used in food containers ���������������������������������������������������������������������������������������������������� is found in the ore zinc blende. �������������������������������������������������������������������������������������������� 
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Calciumhydroxide, Ca(OH)2, is slightly soluble in water. Calciumhydroxide can be made by the reaction of calcium with water. Write the chemical equation for this reaction. Name another substance that reacts with water to form calciumhydroxide. When calciumhydroxide dissolves in water, it dissociates into ions and forms a weakly alkaline solution. Suggest the pH of aqueous calciumhydroxide. Give the formula of the ion responsible for making the solution alkaline. Limewater is a saturated solution of calciumhydroxide, Ca(OH)2. Name the gas limewater is used to test for. Suggest what is meant by the term saturated solution. Describe how you would make a sample of limewater starting with solid calciumhydroxide. Describe how you would test for the presence of calcium ions in a sample of limewater. test observations  A 25.0 cm3 sample of limewater is placed in a conical flask. The concentration of Ca(OH)2 in the limewater is determined by titration with dilute hydrochloricacid, HCl. Name the item of apparatus used to measure the volume of acid in this titration. State the type of reaction which takes place. As well as limewater and dilute hydrochloricacid, state what other type of substance must be added to the conical flask. The equation for the reaction is shown. Ca(OH)2 + 2HCl → CaCl 2 + 2H2O 20.0 cm3 of 0.0500 mol / dm3 HCl reacts with the 25.0 cm3 of Ca(OH)2. Determine the concentration of Ca(OH)2 in g / dm3. Use the following steps. ● Calculate the number of moles in 20.0 cm3 of 0.0500 mol / dm3 HCl.  mol ● Determine the number of moles of Ca(OH)2 in 25.0 cm3 of the limewater.  mol ● Calculate the concentration of Ca(OH)2 in mol / dm3.  mol / dm3 ● Determine the concentration of Ca(OH)2 in g / dm3.  g / dm3  
3
Transition elements are found in the middle block of the PeriodicTable. Chromium has several isotopes. Manganese has only one isotope. State what is meant by the term isotopes. State the nucleon number of manganese. Complete the table to show the number of protons, neutrons and electrons in a 52Cr3+ ion. protons neutrons electrons  One chemical property of transition elements is that they form coloured compounds. Give the colours of the following hydrated salts. ● hydrated copper(sulfate ������������������������������������������������������������������������������������������ ● hydrated cobalt(chloride �����������������������������������������������������������������������������������������  State two other chemical properties of transition elements.  Transition elements and GroupI elements are metals. They share many physical properties including the ability to: ● conduct electricity ● be hammered into shape. Explain why transition elements and GroupI elements conduct electricity. State the property that describes a material which can be hammered into shape. Transition elements and Group I elements differ in other physical properties. Transition elements are harder and stronger than GroupI elements. Describe two other ways in which the physical properties of transition elements differ from GroupI elements.  
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