Solutions of Metals and Non-metals (Page No - 194) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 59:
(a) Which metal is extracted from bauxite ore ?
(b) Give the name of one ore of iron. Which iron compound is present in this ore ? Write its chemical formula.
(c) Describe the extraction of zinc metal from its sulphide ore (zinc blende). Write equations of the reactions involved.
(d) Explain why, the galvanised iron article is protected against rusting even if the zinc layer is broken.
(e) Name a common metal which is highly resistant to corrosion.
Solution :
(a) Aluminium.
(b) Haematite; Iron (III) oxide, Fe₂O₃
(c) Zinc sulphide (zinc blende ore) is strongly heated in air (roasted), it forms zinc oxide and sulphur dioxide. This process is called roasting.

Then, zinc oxide is heated with carbon to form zinc metal. This process is termed as reduction. 

ZnO(s) + C(s) → Zn(s) + CO(g)
(d) The galvanized iron object remains protected against rusting even if a break occurs in the zinc layer because zinc is more easily oxidised than iron. Hence, the zinc continues to corrode but iron object does not corrode or rust.
(e) Aluminium .

Question 60:
(a) Name the metal which is extracted from the ore called ‘rock salt’.
(b) Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae.
(c) Explain how, mercury is extracted from its sulphide ore (cinnabar). Give equations of the reactions involved.
(d) In the electrolytic refining of a metal M, what would you take as anode, cathode and electrolyte ?
(e) Name any five metals which are purified by electrolytic refining method.
Solution :
(a) Sodium.
(b) (i) Calamine; Zinc carbonate, ZnCO₃
(ii) Zinc blende; Zinc sulphide, ZnS
(c) Mercury (II) sulphide ore is roasted in air when mercury (II) oxide is formed.

When this mercury (II) oxide is heated to about 3000C, it decomposes to form mercury metal. 

(d) Anode – Thick block of i mpure metal M
Cathode – Thin strip of p ure metal M
Electrolyte – Water soluble salt (of metal M).
(e) (i) Copper
(ii) Zinc
(iii) Nickel
(iv) Gold
(v) Silver

Question 61:
(a) Which metal is extracted from calamine ore ?
(b) Name one ore of mercury. Which mercury compound is present in this ore ? Write its chemical formula.
(c) How is copper extracted from its sulphide ore (copper glance), Cu₂S ? Explain with equations of the reactions involved.
(d) What is an alloy ? Give two examples of alloys.
(e) How are the properties of an alloy different from those of the constitutent elements ?
Solution :
(a) Zinc
(b) Cinnabar; Mercury (II) sulphide, HgS
(c) The concentrated copper (I) sulphide ore (copper glance), Cu₂S is roasted in air when a part of copper (I) sulphide is oxidised to copper (I) oxide.

When a good amount of copper (I) sulphide has been converted to copper (I) oxide, then the supply of air for roasting is stopped. In the absence of air, copper (I) oxide formed above reacts with remaining copper (I) sulphide to form copper metal and sulphur dioxide.

(d) An alloy is a homogeneous mixture of two or more metals (or a metal and small amounts of non-metals).
Steel and Brass are examples of alloys.
(e) (i) Alloys are stronger than the metals from which they are made.
(ii) Alloys are harder than the constituent metals.
(iii) Alloys are more resistant to corrosion.
(iv) Alloys have lower melting points than constituent metals.
(v) Alloys have lower electrical conductivity than pure metals.