Which of the following pairs will give displacement reactions?
Which of the following methods is suitable for preventing an iron frying pan from rusting?
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:
Food cans are coated with tin and not with zinc because:
The metal that is liquid at room temperature is:
The non-metal that is a good conductor of electricity is:
Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio:
The process of heating a carbonate ore strongly in a limited supply of air is called:
Which metal is obtained by the electrolysis of its molten chloride?
The constituents of solder are:
Why is sodium kept immersed in kerosene oil? (2 marks)
Write the equations for the reaction of (i) iron with steam (ii) calcium and potassium with water. (2 marks)
Why do ionic compounds have high melting points? (2 marks)
What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction. (2 marks)
Name two metals which are found in nature in the free state. (2 marks)
What chemical process is used for obtaining a metal from its oxide? (2 marks)
Metallic oxides of zinc, magnesium and copper were heated with the metals in turn. In which cases will you find displacement reactions taking place? Give a reason. (2 marks)
Why is hydrogen gas not evolved when a metal reacts with nitric acid? (2 marks)
Give reasons: ionic compounds conduct electricity in the molten state but not in the solid state. (2 marks)
What is anode mud? Where is it formed during electrolytic refining? (2 marks)
Roasting of zinc blende is represented by 2ZnS + 3O2 -> 2ZnO + 2SO2. Calculate the mass of zinc oxide formed and the volume of sulphur dioxide produced at STP when 194 g of zinc sulphide is roasted completely. (Zn = 65, S = 32, O = 16; 1 mol of gas = 22.4 L at STP) (3 marks)
Copper is extracted from copper glance by roasting and self-reduction: 2Cu2S + 3O2 -> 2Cu2O + 2SO2 and 2Cu2O + Cu2S -> 6Cu + SO2. Calculate the mass of copper obtained from 477 g of Cu2S. (Cu = 63.5, S = 32) (3 marks)
Calculate the number of electrons transferred when 2 moles of sodium atoms react with chlorine to form sodium chloride. Show the electron transfer for one formula unit with electron-dot structures. (Avogadro number = 6.022 x 10^23) (3 marks)
A sample of 18 carat gold contains 18 parts of gold out of 24. Calculate the percentage of gold and the mass of other metals in a 20 g bracelet. Which metals are usually added? (3 marks)
Write the reaction of magnesium with dilute hydrochloric acid. Calculate the volume of hydrogen gas at STP evolved when 6 g of magnesium reacts completely. (Mg = 24; 1 mol of gas = 22.4 L at STP) (3 marks)
Read the passage and answer the questions. A student took samples of four metals A, B, C and D and added them one by one to solutions of iron(II) sulphate, copper(II) sulphate, zinc sulphate and silver nitrate. Metal A displaced iron and copper but not zinc. Metal B displaced only silver. Metal C showed no reaction with any solution. Metal D displaced iron, copper, zinc and silver. (i) Which is the most reactive metal? (ii) Arrange A, B, C and D in decreasing order of reactivity. (iii) Which metal could be copper? Give a reason. (5 marks)
Read the passage and answer the questions. Mercury is found in nature as cinnabar (HgS). It is extracted by heating the ore in air, which converts it to mercuric oxide, and further heating gives mercury. (i) Name the process of heating a sulphide ore in excess air. (ii) Write the balanced equations for both steps. (iii) Why can mercury be extracted by heating alone, while zinc needs a reducing agent? (5 marks)
Read the passage and answer the questions. Aluminium is one of the most abundant metals in the Earth's crust. It is extracted by electrolysis of its oxide, and it is used in aircraft, utensils and electric cables. It forms a thin layer of oxide on its surface which protects it from further corrosion. (i) Why is aluminium not extracted by reduction with carbon? (ii) What is the nature of aluminium oxide? Write one equation showing this nature. (iii) What is anodising, and why is it done? (5 marks)
Read the passage and answer the questions. Ravi's grandmother wanted to clean her tarnished silver and copper vessels. She used lemon juice for copper vessels and noticed the green coating disappear. (i) What is the green coating on copper vessels? Name the process. (ii) Why does lemon juice remove the green coating? (iii) Name the black coating that forms on silver articles and the gas responsible. (5 marks)
Read the passage and answer the questions. A strip of magnesium burns in air with a dazzling white light to form a white powder. The white powder is dissolved in water and the solution is tested with litmus. Separately, sulphur powder is burnt and the gas formed is dissolved in water and tested. (i) Write the balanced equations for the burning of magnesium and of sulphur. (ii) What colour changes are seen with red and blue litmus in each case? (iii) What general conclusion can be drawn about metallic and non-metallic oxides? (5 marks)
Compare the physical and chemical properties of metals and non-metals. Write balanced equations for the reactions of metals with oxygen, water and dilute acids, giving one example each, and explain the exceptions in physical properties. (6 marks)
Explain the formation of ionic compounds with the help of electron-dot structures for NaCl and MgCl2. List four properties of ionic compounds and explain why they conduct electricity in the molten state and in aqueous solution. (6 marks)
Describe the extraction of metals of medium reactivity with the example of zinc. Explain roasting and calcination with balanced equations, and the reduction of the oxide with carbon. Draw a flow chart of the steps, and explain why the thermit reaction is used to join railway tracks. (6 marks)
What is electrolytic refining? Describe the electrolytic refining of copper with a labelled diagram. Write the reactions at the cathode and anode and explain where the impurities go. (6 marks)
What is corrosion? Describe an experiment with three test tubes, with a labelled diagram, to show that both air and water are needed for rusting. Explain four methods of preventing corrosion, and state the composition and one use each of stainless steel, brass and bronze. (6 marks)
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