Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Two ores A and B were taken. On heating ore A gives CO₂ whereas, ore B gives SO₂ .What steps will you take to convert them into metals?

What is an alloy? How is an alloy made? List two purpose of making alloys. Mention the constituents and two properties of each of the following alloys.
(i) Stainless steel
(ii) Brass

(i) Why Sulphuric acid is called the 'king of chemicals'?
(ii) Name the gas evolved when :
      (a) Concentrated Sulphuric acid acts on Sulphur.
      (b) Dilute Sulphuric acid acts on Sodium carbonate.
(iii) State the colour change you would observe on adding concentrated sulphuric acid to :
      (a) Blue Copper sulphate crystals.
      (b) Colourless cane-sugar crystals.

(a) Write chemical equations for the reactions involved in obtaining pure alumina from the mineral bauxite which has impurities of iron oxide and silica.
(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina.

(a) What is corrosion of metals? Name one metal which does not corrode and one which corrodes on being kept in atmosphere.
(b) How will you show that the rusting of iron needs oxygen and moisture at the same time?

(a) What is an 'activity series' of metals? Arrange the metals Zn, Mg, Al, Cu and Fe in a decreasing order of reactivity.
(b) What would you observe when you put
       (i) Some zinc pieces into blue copper sulphate solution?
       (ii) Some copper pieces into green ferrous sulphate solution?
(c) Name a metal which combines with hydrogen gas. Name the compound formed.

(a) Name one main ore of Aluminium. Write its formula. Which two main impurities are associated with this ore?
(b) Describe with chemical equations, the method employed for the enrichment of the above named ore.

How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium.

A man went door to door posing to be a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument, the man beat a hasty retreat.
(i) Can you play the detective to find out the nature of the solution he had used?
(ii) What is 24 carat gold?