Coupon Accepted Successfully!



a) Due to which property of metals are metallic foils prepared?
b) Write uses of aluminium foils?

a) Metallic foils are prepared, making use of the malleable property of metals.

b) Aluminium foils are used for
(i) wrapping chocolates and food stuff
(ii) to prepare hydrogen.


Name one non-metal and one metal, which are in liquid state at room temperature.

Bromine is the non–metal and mercury is the metal which are in liquid state at room temperature.


Give reasons for the following
i) Zinc oxide is considered an amphoteric oxide.
ii) Non-metals in general do not displace hydrogen from dilute acids.
iii) Metals conduct electricity.

i) Zinc oxide is considered an amphoteric oxide because it shows both acidic and basic behaviour.
ii) Non-metals do not react with dilute acids hence do not displace hydrogen from dilute acids.
iii) thatMetals conduct electricity because they contain free electrons which can move easily through the metal and conduct electric current.


Identify the following oxides with neutral, acidic, basic and amphoteric oxides.
 i) Al2O3  ii) MgO iii) SO2  iv) CO;  v) Na2O vi) N2O vii) ZnO viii) CO2  ix) SO3 x) CaO.

Neutral oxides: CO; N2O

Acidic oxides: SO2; CO2; SO3

Basic oxides: MgO; Na2O; CaO

Amphoteric oxides: Al2O3 ; ZnO


By what processes do you concentrate the following ores:
i) PbS(galena)
ii) Fe2O3(haematite)
iii) Al2O3.2H2O (bauxite)

i) PbS (galena) is concentrated by froth floatation method.

ii) Fe2O3 (haematite) is concentrated by magnetic separation.

iii) Al2O3.2H2O (bauxite) is concentrated by leaching process (chemical method).


Why is that iron does not occur as a metal in the crust of the earth? What are the common compound forms in which iron occurs? Which of these is more often used for extracting iron? Why are carbon and limestone mixed with iron ore before feeding it into the blast furnace? Write the chemical equations for the reduction step and the slag formation step.

Iron is quite reactive and so it does not occur as a metal in the crust of the earth. The common compounds formed are its oxide, a carbonate and a sulphide. The oxide ore of iron called haematite is more often used for extracting iron. The carbon and limestone which is mixed with iron ore is called the charge. This charge is responsible for the formation of iron metal. Coke acts the reducing agent and addition of limestone helps to remove the earthy impurities like sand from the blast furnace by forming fusible slag.

Reduction of Iron(III)oxide or haematite to Iron: carbon monoxide reduces iron(III)oxide to iron metal
Fe2O3(s) + 3CO(g) 2Fe +3Co2 (g)

i) In the blast furnace limestone decomposes to form calcium oxide and carbon dioxide.
CaCO3 (s) CaO(s) +CO2(g)

ii) This calcium oxide reacts with sand for form molten calcium silicate called slag.
CaO(s) + SiO2 CaSiO3(l)


By what chemical processes do you obtain the following metals?
i) Mercury from HgO ii) Iron from Fe2O3  iii) Manganese from MnO2  iv) Sodium form NaCl v) Aluminium from Al2O3.

i) Mercury from mercuric oxide can be obtained by simple heating.
2HgO 2Hg + O2

ii) Iron from iron oxide (Fe2O3) can be obtained by carbon reduction method i.e heating with coke.
2C + O2   2CO
Fe2O3 + 3CO   2Fe + 3CO2

iii) Manganese from manganese dioxide is obtained by alumino thermite process, i.e. heating with aluminium.
3MnO2 + 4Al   2Al2O3 + 3Mn

iv) Sodium from sodium chloride is obtained by electrolytic reduction (electrolysis) of fused NaCl.
NaCl   Na+ + Cl-
At anode 2Cl-   Cl2 + 2e-
At cathode 2[Na= +e-   Na]

v) Al2O3   2 Al3+ + 3(O)2-
At cathode 4[2Al3+ + 6e   2Al]
At anode 6O2-   3O2 + 12e-.


i) What is the composition of molten slag, formed in the extraction of iron in the blast furnace?
 ii) What is the use of slag?

i) Molten slag in the extraction of iron is calcium silicate(CaSiO3).

ii) Slag is used for constructions of roads.


Write the name of the compound, when iron is corroded?

When iron is corroded rust is formed which is hydrated iron (III) oxide (Fe2O3.x.H2O)


Give reasons for the following

i. Na, K and Ca metals form hydrides by combination with hydrogen gas, but most other metals do not.
ii. Aluminium easily combines with oxygen but still it can be used for making kitchen utensils.

i. Metals like Na, K and Ca can force the hydrogen atoms to accept electrons given by them and form hydrides.

ii. Aluminium forms a protective oxide layer when it combines with oxygen and hence it is used for making kitchen utensils.


i) Among iron and aluminium which rusts easily?
ii) What are the conditions, necessary for rusting of iron?

i) Among iron and aluminium, iron rusts easily. It forms Al2O3. That is why iron pipes are wrapped with aluminium metal to prevent rusting of iron.

ii) 1) Air or oxygen 2) Water, containing dissolved air.
These are necessary conditions for rusting of iron.


Name an ore of zinc other than zinc oxide. By what process can this ore be converted to zinc oxide.

Zinc blende(ZnS) is an ore of zinc other than zinc oxide. Roasting is the process by which ZnS can be converted into zinc oxide.


What property of hydrogen is observed in the following experiments?
i) Balloon, filled with hydrogen, floats.

ii) Pop sound is heard when a burning splint is introduced at the mouth of hydrogen filled jar.

iii) When black cupric oxide is heated in a stream of hydrogen, reddish colour is obtained.

i) Hydrogen is light. So hydrogen filled balloons float.

ii) Pop sound is due to the combustible property of hydrogen. Hydrogen burns with oxygen at the mouth of the hydrogen filled jar.

iii) Hydrogen has reducing property. Hence it reduces black cupric oxide to red copper metal.


Select the non-metals amongst the following
i) Bismuth   ii) Sulphur   iii) Arsenic   iv) Hydrogen.

Hydrogen and Sulphur are the non-metals.


How do you test ammonia gas?

Ammonia gas is tested, by showing a drop of conc. HCl by means of a glass rod to it, when dense white fumes of ammonium chloride are formed.

NH3 + HCl NH4Cl

Ammonium chloride (dense white fumes).


Write chemical equations for reactions taking place when
i) Cinnabar is heated in air.
ii) Concentrated sulphuric acid and sulphur are heated together. Calcium metal reacts with water.

i) Cinnabar is heated in air
2HgS + 3 O2 (g) 2HgO(s) + 2SO2

ii) Calcium metal reacts with water.
Ca(s) + 2H2O (l) Ca(OH)2(aq) + H2 (g)


What are the uses of ammonia?

i) Ammonia is used in the manufacture of fertilizers like ammonium sulphate and ammonium nitrate.

ii) To manufacture nitric acid by Ostwald’s process.

iii) To prepare dyes, explosives, cellulose acetate etc.


Why do some metals like, Na, K, Ca, Mg not occur in nature as free elements?

Metals like Na, K, etc (alkali metals) and Ca, Mg etc (alkaline earth metals) are very reactive and hence they react with atmospheric oxygen and carbon dioxide and also with other non-metals like sulphur present in the earth’s crust to form compounds like oxides, carbonates, sulphides, sulphates and chlorides. So they do not occur in free state, but are found in the form of the above compounds.


Write chemical equations for reactions taking place when:
i) Manganese dioxide is heated with aluminium powder.
ii) Steam is passed over hot iron.
iii) A mixture of ammonia and oxygen is passed over platinum heated to 1073 K.

i) Manganese dioxide is heated with aluminium powder.
3MnO2 (s) + 4Al (s) 3Mn(l) + 2Al2O3

ii) Steam is passed over hot iron.
3Fe(s) + 4H2O Fe3O4 (s) +4H2

iii) A mixture of ammonia and oxygen is passed over platinum heated to 1073K
4 NH3 (g) + 5O2(g) 4NO(g) + 6H2O


Why are metals like sodium, calcium, magnesium, aluminium etc. obtained by electrolytic reduction?

Metals like Na, Ca, Mg, Al etc, which are high up in the activity series are electropositive elements and possess a high affinity for oxygen. So their oxides are very much stable and cannot be reduced with common reducing agents like carbon. So carbon reduction process cannot be applied to prepare these metals. They can only be prepared by electrolytic reduction of their fused chlorides or oxides.


State briefly how you will extract iron from its ore. Draw a neat and labelled diagram. Write all the chemical reactions involved in it.

Iron is usually extracted from its chief ore, Haemitite.
The various steps involved in the production of iron metal from haematite are as follows:

1. Concentration of ore
The concentration of haematite or is done by the method of hydraulic washing. The ore is spilt into small pieces and then washed in a stream of water to remove sand, clay. In this way ,a fairly concentrated ore is obtained and usually there is no need of any further concentration.

2. Calcination
The washed iron ore is then strongly heated in the absence of air to expel water sticking to it.

3. Reduction
The washed and dried ore is mixed with weighed quantities of coke and limestone and put into a blast furnace from the top .A blast of hot air is blown into the furnace from near its bottom. This air is to supply for the burning of coke.
The two reactions which take place in the blast furnace leading to the formation of iron metal are: formation of carbon monoxide and reduction of haematite.

1) Formation of carbon monoxide
Carbon monoxide is the main reducing agent in the extraction of iron by blast furnace. Carbon monoxide is formed from coke in two steps:
Near the bottom of the furnace coke burns in air to form carbon dioxide and a lot of heat is produced
C (s) + O2 CO2 + Heat
In the center of the furnace, carbon dioxide reacts with white hot coke to form carbon monoxide.
CO2 + C(s) 2 CO

2) Reduction of Iron (III) oxide to Iron
In the upper part of the furnace, carbon monoxide reduces iron (III) oxide to iron metal
Fe2O3 + 3CO 2Fe(l) +3CO2(g)
Iron metal is produced as a grey solid which melts as it comes down in the furnace where the temperature is very high. Molten iron collects at the bottom of the furnace.


Write the chemical formula for the following.
a) Alumina b) Silica c) Rust d) Oleum e) Slag f) Sodium amalgam g) Bauxite h) Haematite.

a) Alumina - Al2O3
b) Silica - SiO2
c) Rust - Fe2O3. xH2O
d) Oleum - H2S2O7 (SO3, dissolved in H2SO4)
e) Slag - CaSiO3
f) Sodium amalgam - Na – Hg (an alloy of sodium with mercury)
g) Bauxite - Al2O3.2H2O
h) Haematite - Fe2O3



In Frasch process of digging out sulphur from a deep underground, how has it made possible to life sulphur from the bed to surface of each? What is the basic principle on which extraction of sulphur is based? Draw a neat and labelled diagram. Besides elemental form, in what compound forms is sulphur found. Give two physical properties of sulphur.

In the Frasch process in order to bring out sulphur from the underground deposits, a hole of about 30 cm diameter is bored up to the sulphur bed. It is based on the principle that sulphur has a comparatively low melting point of 1150 or 3880 due to which it can be melted by introducing super-heated water in the underground sulphur deposits. This mixture of molten sulphur and water is then brought out by the force of hot, compressed air.
Three concentric pipes A, B, C of different diameters are put down in the boring.  

The three pipes are arranged one inside the other as shown in the above figure. Super-heated water under pressure is forced down through the outermost pipe A. The heat given out by hot water melts the underground sulphur. A jet of hot, compressed air is then sent down through the innermost pipe C. The force of compressed air brings the mixture of molten sulphur and water through the central pipe B. The sulphur water emulsion is kept in settling tanks when sulphur gets cooled and separates from water in the form of a yellow solid. The sulphur obtained by this method is 99.5% pure.


The copper vessels used in homes are found to be coated with green colour. Answer the following.
a) What is the chemical composition of the green coating?
b) Why do copper vessels form such a green coating?
c) What is the name of the phenomenon, responsible for the green coating?
d) Copper vessels are best cleaned with tamarind or lemon juice, but not with soap. Why?

a) Green coloured coating on copper is due to the formation of basic copper carbonate, CuCO3.Cu(OH)2.

b) Copper forms green coating of basic copper carbonate as it reacts with water, atmospheric oxygen and carbon dioxide.

c) Corrosion phenomenon is responsible for the formation of basic copper carbonate (green).

d) Since basic copper carbonate is basic in nature, it can be removed by tartaric acid present in tamarind or citric acid, present in lemon. Soap is basic in nature. So copper vessels are best cleaned with tamarind or lemon.


Give reasons for the following
i. Silicon counts among metalloids
ii. Carbon is not used for making aluminium from aluminium oxide.
iii. For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc.

i. Silicon shows properties of both metals and non-metals and hence silicon counts among metalloids.

ii. Carbon has less affinity for oxygen than Aluminium and hence it cannot eliminate oxygen from Aluminium oxide.

iii. Zinc granules are preferred to a block of zinc because it offers a large surface area for the reaction with the acid.


i) Why sugar chars (turns black) when conc. H2SO4 is added to it?
ii) What is the blue colour of crystalline copper sulphate due to?

i) Conc.H2SO4 is a dehydrating agent. Sugar is C12H22O11. When conc. H2SO4 reacts with sugar, it removes hydrogen and oxygen atoms from the sugar molecules in the form of water, leaving behind carbon. So sugar becomes black or get charred with conc. H2SO4.

C12H22O11 12C(s) + 11H2O(l)

ii) Blue colour of crystalline copper sulphate is due to five water molecules of hydration in CuSO4 5H2O.


Write chemical equations for reactions taking place when
i. Zinc carbonate is calcined.
ii. Ammonia gas is passed over heated copper (II) oxide.

(i) ZnCO3 ZnO + CO2
(ii) 3CuO (s) +2NH3 Cu(S) +N2(g)+3H2O


(i) What is the colour of potassium dichromate solution?
(ii) What is the colour of Cr3+ ion?
(iii) What property of SO2 is responsible for bringing change of colour of potassium dichromate?

(i) Potassium dichromate solution is orange yellow colour.

(ii) The colour of Cr3+ ion is green.

(iii) Reducing property of sulphur dioxide is responsible to change the orange yellow colour of K2Cr2O7 to green colour.


How is chloride of lime chemically different from calcium chloride? Why does chloride of lime gradually lose its chlorine when kept exposed to air?

Chemically, chloride of lime is calcium oxy chloride, CaOCl2, also called bleaching powder. When exposed to air it gradually lose its chlorine because it reacts with carbon dioxide present in air to produce calcium carbonate and chlorine gas.


Write short notes on the bleaching action of sulphur dioxide.

a) Sulphur dioxide bleaches the vegetable colours in the presence of moisture.

b) It bleaches the vegetable colours by reduction. It removes oxygen from coloured material.

c) Its bleaching action is temporary, because atmospheric oxygen again oxidises the bleached article back to its original colour.

d) SO2 is used to bleach delicate fabrics like wool, silk etc.


(a) What is the atomicity of sulphur?
(b) How do you bring the change of rhombic sulphur to monoclinic sulphur and vice versa?
(c) What is the action of conc. HNO3 on sulphur?

(a) Atomicity of sulphur is 8. Its formula is S8.

(b) Rhombic sulphur, when heated to above 369K, changes to monoclinic sulphur. Monoclinic sulphur, on cooling to below 369 K reverts back to rhombic sulphur.
Rhombic sulphur Monoclinic sulphur

(c) Conc. HNO3 oxidises sulphur to sulphuric acid while the former is reduced to NO2.

S(s) + 6HNO3(aq) H2SO4(aq) + 6NO2(g) + 2H2O(l).


Name two metals used in making fuse wires.

Copper and Aluminium are the two metals used in making fuse wires.


(i) How can ammonia be converted to NO2 and nitric acid?
(ii) What is liquor ammonia?

(i) When ammonia is oxidised by heating with oxygen to 1073 K in the presence of platinum gauze, reddish brown vapours of NO2 are formed.
4NH3 + 5O2 4NO + 6H2O

2NO + O2 2NO2
When NO2 dissolves in water, nitric acid is formed.
2NO2 + H2O+ O 2HNO
Thus HNO3 is manufactured from ammonia.

(ii) A saturated solution of ammonia is known as liquor ammonia.


Complete the following reactions

i) CH3COONa + C2H5OH

ii) CH3CHO + H2O


Define the following terms
i) Mineral
ii) Ore
iii) gangue

i) The inorganic elements or compounds which occur naturally in the earth’s crust are known as minerals.

ii) The minerals from which a metal can be profitably extracted are called ores.

iii) The impurity of sand and rocky materials present in the ore is known as gangue.


a) State why hydrogen is said to be a clean fuel?
b) What property of hydrogen is involved in being a good fuel?
c) What is hydrogenation of oils? Write one application.

a) Hydrogen is a clean fuel because its reaction with oxygen produces only water. It does not form gases like CO2, NO2 etc, which pollute air.

b) Hydrogen, on combustion with oxygen, produces water and a lot of heat. This is an exothermic reaction.

c) Oils are unsaturated molecules, containing double bond. So hydrogen atoms are added at the double bonds of the molecules of oil. The reaction of hydrogen with oils is known as hydrogenation.
The hydrogenation reaction takes place at 473 K and in the presence of nickel catalyst.
Vanaspati or dalda ghee is prepared by hydrogenation of vegetable oils.


What is the formula of Ammonia? Write the flow diagram for the manufacture of ammonia by Haber’s process. State any two of its physical properties. Write the equation for its reaction with HCl.

The formula of Ammonia is NH3.
The flow diagram of the manufacture of ammonia by Haber's process is given below:

Physical Properties

1. Ammonia is a colourless gas having a characteristic pungent smell.
2. Ammonia is highly soluble in water.


How do metals react with hydrogen? Explain with an example.

Only very few reactive metals like sodium, potassium, calcium and magnesium react with hydrogen to form metal hydrides. Example when hydrogen gas is passed overheated sodium, sodium hydride is formed.


Name a metal which is stored in kerosene oil.

Sodium is a metal which is stored in kerosene oil.


Metals are electropositive in nature. Explain.

Metals are electropositive in nature because they can form positive ions by the loss of electrons.


Explain the displacement of hydrogen by a metal from an acid with an example. Give the equation to support the same.

Metals usually displace hydrogen from acids. For example sodium metal reacts with dilute hydrochloric acid to form sodium chloride and hydrogen.
2Na(s) + 2HCl (aq) 2NaCl (aq) + H2 (g)


Why is sodium kept in kerosene?

Sodium reacts so vigorously that they catch fir if it is kept in the open air and hence sodium is kept in kerosene.


Name the element or compound which is associated with Hall’s process.

Aluminium is associated with Hall’s process.


Which metal is used in nuclear reactors and aerospace projects?

Aluminium is used in nuclear reactors and aerospace projects.

Test Your Skills Now!
Take a Quiz now
Reviewer Name