CHAPTER 5 METALS AND NON-METALS
Textual question: (Page no.92)
Q.1. Name five metals and non-metals.
Ans:-
Five metals : sodium, potassium, aluminium, magnesium and copper.
Five non-metals: sulphur, chlorine, bromine, hydrogen and carbon.
Q.2. Name one metal and one non-metal which exist in liquid state at room temperature.
Ans:- One metal that exist in liquid state at room temperature is mercury and the non-metal that exist as liquid is bromine.
Q.3. Give an example of metal which
i)Can be easily cut with a knife?
ii)Is the best conductor of heat?
iii)Is a poor conductor of heat?
Ans:-
i) Sodium
ii) Silver
iii) Mercury
Q.4. What is meant by saying that metals are malleable and ductile?
Ans:- Metals are malleable means they can be beaten into sheets and ductile means they can be drawn into wires.
Q.5. Which property of copper and aluminium make them suitable for making electric wires?
Ans:- The property of copper and aluminium being good conductors of electricity makes them suitable for making electric wire.
Q.6. Name a non-metal which conduct electricity.
Ans:- Carbon in the form of graphite.
Q.7. Write the equations for the reactions.
a)potassium with water
b)red hot iron with steam
c)zinc with dilute sulphuric acid
Ans:-
a)Potassium with water -
2K + 2H2O →2KOH + H2
b)Red hot iron with steam -
3Fe + 4H2O → FeOFe2O3 + 4H2
c)Zinc with dilute sulphuric acid -
Zn + H2SO4 → ZnSO4 + H2
Q.8. How do metals differ from non-metals in their reaction with oxygen and product is dissolved in water.
Ans:- Metals react with oxygen to form basic oxide and basic oxide dissolves in water to form alkalis.
Eg.
4Na + O2 → 2Na2O
Na2O + HO2 → 2NaOH
Non-metals react with oxygen to give acidic oxides which ion dissolving in water form acids.
E.g.
S(s) + O2 (g) → 2SO2(g)
SO2(g) + H2O(l) → H2SO3(l)
Ans:- Gold and silver
Q2. Define the following terms –
i) Mineral ii) Ores iii) Gangue
Ans:-
i)Mineral- The natural material in which the metals or their compounds are found in earth’s crust is called minerals.
ii)Ores- Ores are those minerals from which metals can be extracted profitably.
iii)Gangue- The unwanted impurities such as earthy, sandy and rocky materials associated with the ores are called gangue or matrix.
Q.3. Differentiate between roasting and calcinations.
Ans:-
|
DIFFERENCE |
|
|
ROASTING |
CALCINATION |
|
1.
It
is the process of strong heating an ore in the presence of air |
1. It is the process of
heating an ore strongly in
limited supply of air. |
|
2. In this process, a sulphide ore is converted into oxide. |
2. In this
process, a carbonate ore is converted into oxide. |
Q.4. Name two sulphide and two oxide ore. Ans:-
Two sulphide ores – Iron pyrite (FeS), copper pyrite(𝐶𝑢𝐹𝑒𝑆2)
Two oxide ores – Bauxite (𝐴𝑙2𝑂32𝐻2𝑂), Haematite (𝐹𝑒2𝑂3)
Q.5. Name the systematic steps involved in metallurgy.
Ans:-
(i)Concentration or enrichment of ores
(ii)Extraction of metal from the concentrated ores
(iii)Refining or purification of the impure metal
Q.6. Write the chemical process used for obtaining a metal from its oxide.
Ans:- The chemical process is reduction. In this process the oxides of metals are mixed with coke, carbon monoxide or other element which has high affinity for oxygen.
Q.7. Give an example of a sulphide ore which is reduced to metal by heating alone. Give the relevant equation involved.
Ans:- Cinnabar (HgS) is the sulphide ore.
The relevant equation is
Q.8. Why aluminium cannot be obtained by reduction of its oxide with coke?
Ans:-Aluminium cannot be obtained by reduction of its oxide with coke because the affinity of oxygen for the metal is greater than its affinity for carbon.
Q.9. Explain how the following metals can be obtained from their compounds by reduction process
(a)Metal X which is low in activity series.
(b)Metal Y which is moderately reactive.
(c)Metal Z which is high in the reactivity series.
Ans:-
(a)Metal X is low in reactivity the sulphur and oxides of these metals can be reduced to metals by heating alone.
(b)Metal Y is moderately reactive
The sulphide or carbonate ore of these metals is converted into corresponding metal oxides before reduction.
The oxides of this metal react with suitable quantity of coke on carbon monoxide on other elements having affinity for oxygen to form metal.
E.g. ZnO(s) + C(s) →Zn(s) + CO(g)
(c)Metal Z is highly reactive and has great affinity for oxygen. So the metal is obtained by electrolytic method.
Sodium can be manufactured by electrolysis of fused sodium chloride.
E.g.
fusion
NaCl(s) –––--→ Na+(l)+ Cl−(l)
At cathode
Na+ + e− → Na[reduced]
At anode
2Cl− → Cl2 + 2e−[oxidation]
Q.10. An alloy solder is used in electronic industry to join different electronic components. What are the constituents of their alloy?
Ans:- The constituents of solder is lead(40-60)% and tin(40 -60%).
Q.11. Which alloy is used for making bodies of aircrafts? What is the approximate composition?
Ans:- Duralumin is used for making aircrafts. The approximate composition is Aluminium - 95%
Copper – 4%
Manganese – 0.5%
Magnesium – 0.5%
Textual Question (Page 107)
Q.1. Give five points to distinguish metals from non-metals.
Ans:- Five points to distinguish metals from non-metals
|
DIFFERENCES |
|
|
METALS |
NON-METALS |
|
1. Metals are
malleable and ductile |
1. Non-metals are not malleable and ductile |
|
2.
Metals
are good conductors of heat and electricity |
2. They are poor
conductors of heat and conductor
electricity except graphite. |
|
3. Metals are
lustrous or shiny |
3. Non-metals are not
lustrous |
|
4.
Generally
metals are strong and have high tensile strength |
4. Generally they are weak
and have low tensile
strength |
|
5.
They
have high melting and boiling point except mercury. |
5. They have low melting
and boiling point except carbon
and silicon |
Q.2. You are given a hammer, a battery, a bulb wires and a switch
(a) How would you use them to distinguish between samples and metals and non-metals.
(b) Assess the usefulness of these tests.
Ans:-
If the sample can be beaten into sheets by hammering, then the sample is a metal and if it is broken into pieces then it is non-metal.
An arrangement is set up as shown in the figure.
If the bulb starts glowing then the sample is metal, as metal is a good conductor of electricity.
If the bulb does not glow, then the sample is non – metal. Usefulness of these tests:
These tests can be used for identifying metals with the exception of some metals like sodium, potassium.
Metals can be beaten into sheets and can be used to cover food items.
E.g. Aluminium foil.
Q.3. Frying pans and boilers are generally made of aluminium but not from steel.why? Give reasons.
Ans:- Frying pans and boilers are generally made of aluminium but not from steel because the thermal conductivity of aluminium is higher than steel and moreover it is resistant to corrosion.
Q.4. Distinguish between metals and non-metals on the basis of their chemical properties. Give three points.
Ans:-
|
DIFFERENCES |
|
|
METALS |
NON-METALS |
|
1.
Oxides
of metals are basic in nature |
1.
Oxides
of non-metals are acidic or neutral in nature. |
|
2.
Metals
react with dilute acids to release hydrogen. |
2.
Non-metals
do not react with dilute acids. |
|
3.
Metals
displace hydrogen from water. |
3.
Non-metals
do not react with water. |
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