Choose one most, appropriate response out of the four provided to you.
Which of the following metal cannot produce hydrogen gas by reacting with water-
(a) Zn
(b) Cu
(c) Mg
(d) Ca.
Ans:- (b) Cu
(ii) Which of the following reaction does not take place?
Ans:-
Which of the following metals cannot displace silver from an aqueous solution of silver nitrate.
(a) Cu
(b) Zn
(c) Au
(d) Fe.
Ans:- (c) Au
The ore which is purified by froth floatation process is-
(i) Limestone
(ii) Hematite
(iii) Bauxite
(iv) Galena.
Ans:- (iv) Galena.
Which of the following ores can be concentrated by a froth-flotation process?
(a) Zinc blende ZnS
(b) Horn Silver AgCl
(c) Haematite Fe2O3
(d) Bauxite Al2O3.2H2O
Ans:- (a) Zinc blende ZnS
The metal which exists in the liquid state at normal temperature is-
(a) Bromine
(b) Potassium
(c) Copper
(d) Mercury
Ans:- (d) Mercury
A ferrous alloy is-
(a) Nickel steel
(b) Inver
(c) Brass
Ans:- (a) Nickel steel
The number of electrons present in the valence shell of the metals is –
(a) 1,2 or 3
(b) 2,3 or 4
(c) 4,5 or 6
(d) 5,6 or 7
Ans:-(a) 1,2 or 3
The amphoteric oxide is
(a) Na2O
(b) Mn2O7
(c) CO2
(d) ZnO
Ans:- (d) ZnO
Which one of the following metals is a bad conductor of heat
(a) Cu (b) Fe (c) Mg (d) Bi
Ans:- (d) Bi
Which one of the following is the best conductor of Electricity
(a) Fe (b) Ca (c) Sn (d) Cu
Ans:- (d) Cu
Iron fillings were added to copper sulphate solution taken in a beaker. Which one of the following will occur?
(a) Iron fillings remain grey but the solution remains blue.
(b) lron fillings remain grey but solution becomes green.
(c)Iron fillings become reddish brown and the solution becomes green.
(d) Iron fillings become reddish brown and solution remain blue.
Ans:- (c)Iron fillings become reddish brown and the solution becomes green.
When Zinc rod is placed in copper sulphate solution, the blue colour of the solution starts fading. This is due to –
(a) Oxidation of zinc.
(b) reduction of copper ions.
(c) Oxidation of SO2-4 ions.
(d) reduction of copper SO2-4 ions.
Ans:- (a) Oxidation of zinc.
Without any reaction, which of the following solutions can be stirred with an aluminium rod?
(a) CuSO4
(b) FeSO4(aq)
(c) ZnSO4
(d) None
Ans:- (d) None
Which of the following is the strongest reductant?
(a) Al (b) Zn (c) Fe (d) Cu
Ans:- (a) Al
Copper Sulphate solution should not be kept in-
(a) Iron vessel
(b) Aluminium vessel
(c) zinc vessel
(d) any of these vessels
Ans:- (d) any of these vessels
On putting a few drops of liquid on a PH strip, the colour of the PH strip changed to green. The liquid is most probably-
(a) NaOH solution
(b) dilute HCl
(c) water
(d) lemon juice.
Ans:- (c) water
An aqueous solution of sodium bicarbonate is diluted, its PH
(a) decreases
(b) increases
(c) remains the same
(d) cannot be predicted
Ans:- (b) increases
Zinc reacts with NaOH solution to produce-
(a) NO2 (b) NH3 (c) H2 (d)O2
Ans:- (c) H2
Which one of the following metals does not react with cold as well as hot water?
(a) Ca (b) Na (c) Fe (d) Mg
Ans:- (c) Fe
Which one of the following properties is not generally exhibited by ionic compounds?
(a) High melting and boiling points
(b) Electrical conductivity in the molten state
(c) Electrical conductivity in solid state
(d) Solubility in water
Ans:- (c) Electrical conductivity in solid state
Silver articles become black on prolonged exposure of air. This is due to the formation of-
(a) Ag3N
(b) Ag2O
(c) Ag2S
(d) Ag2S and Ag3N
Ans:- (c) Ag2S
Which of the following non-metals is a liquid –
(a) bromine
(b) phosphorous
(c) sulphur
(d) carbon
Ans:- (a) bromine
Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity-
(a) sulphur
(b) fluorine
(c) graphite
(d) diamond
Ans:- (c) graphite
Which among the following alloys contain mercury as one of its constituents?
(a) solder
(b) Zinc amalgam
(c) Alnico
(d) stainless steel
Ans:-(b) Zinc amalgam
Which of the following non-metal is lustrous?
(a) Cu and Au
(b) Ni and Cu
(c) Cu and Cr
(d) Ni and Cr
Ans:- (a) Cu and Au
In stainless steel, Iron is mixed with-
(a) Cu and Au
(b) Ni and Cu
(c) Cu and Cr
(d) Ni and Cr
Ans:- (d) Ni and Cr
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for same?
(1) Good thermal activity
(2) Good electricity conductivity
(3) Ductility
(4) High melting point
(a) 1 and 2(b) 1 and 3(c) 2 and 3(d) 1 and 4
Ans;- (d) 1 and 4
The poorest conductor of heat among metals is —
(a) Mercury
(b) Sodium
(c) Calcium
(d) Lead
Ans:- (d) Lead
The unwanted earthy impurities like sand, limestone, rocky materials present in the ore are called —
(a) metallurgy
(b) refining
(c) calcination
(d) gangue
Ans:- (d) gangue
Example of an amphoteric oxide-
(a)Al2O3
(b) Na2O
(c) CO
(d)CO2
Ans:- (a)Al2O3
The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called-
(a) Reduction
(b) Calcination
(c) Roasting
(d) Smelting
Ans:- (b) Calcination
Galvanisation is a method of protecting iron from rusting by coating with a thin layer of-
(a) Aluminium (b) silver
(c) Gallium (d) Zinc
Ans:- (d) Zinc
An element X is soft and can be cut with a knife, This is very reactive to air and cannot be kept open in the air. It reacts vigorously with water. Identify the element from the following-
(a) Mg (b) Na (c) P (d) Ca
Ans:- (b) Na
Which of the following property is generally not shown by metals?
(a) Ductility (b) Dullness
(c) Sonorous in nature (d) Electrical conduction
Ans:- (b) Dullness
Which of the following metals are obtained by electrolysis to their chlorides in molten states?
(a) Na (b) Ca (c) Fe (d) Cu.
Ans:- (a) Na and (b) Ca
Which among the following alloys contain mercury as one of its constituents?
(a) Zinc amalgam (b) Solder
(c) Almico (d) stainless steel
Ans:-(a) Zinc amalgam
Which among the following alloys contain non-metal as one of its constituents?
(a) Brass (b) Bronze
(c) Amalgam (d) Steel
Ans:- (d) Steel
An alloy is-
(a) an element
(b) a homogeneous mixture
(c) an element mixture
(d) a heterogeneous mixture
Ans:- (b) a homogeneous mixture
Fill in the blanks:
During electrolysis —— accept electrons from a cathode and is reduced to metal.
Ans:- Metal Ions
In calcination and roasting process—– or —— ores are converted to oxide.
Ans:- carbonate, sulphide.
The Aluminium oxide present in Bauxite reacts with sodium hydroxide and dissolves as ——
Ans:- oxide layer
The ore tinstone contains ——- as the main impurity.
Ans:- wolframite
In Froth Floatation process —— ores of the metals are concentrated.
Ans:- sulphide
The substance which is formed by reacting between ‘Gangue and Flux is called ——
Ans:- slag
Very reactive metals always present as ——-
Ans:- molten salt
When the tendency to lose electron increases ——- of metal also increases.
Ans:- metallic character
Stainless steel contains Iron and other metals like—-,—–, —–and —–.
Ans:- N, Cr, Mo
The Magnelium alloy contains —— and ——- metal.
Ans:- Mg, Al
A—— alloy is used to make different parts of an aeroplane.
Ans:- Aluminium
The main impurities present in bauxite ores are —— and ——-.
Ans:-hamatite, sand.
Two soft metals are ——- and ——.
Ans:-Na, K
When steam is passed over red hot iron —— and —– are produced.
Ans:-Iron oxide (ii, iii) and hydrogen.
Magnelium is an alloy of——- and ——-.
Ans:-Mg, Al
In metallurgy ——- reacts with —— to form slag.
Ans:-Gangue, flux.
——- ores of metals are ——- by froth floatation process.
Ans:-sulphide, extracted.
Brass is an alloy of —— and ——.
Ans:-Cu and Zn
When copper wire is dipped in a silver nitrate solution ——- and —— are produced.
Ans:-Copper nitrate, silver.
Metals can form positive ions by ——-.
Ans:-losing electron.
The metals in the middle of the activity series such as iron, zinc, lead, copper etc. are moderately reactive and these are usually present as —– or —–.
Ans:-carbonates, sulphides.
State whether the following statements are true or false:
Amphoteric oxides are neutral oxides.
Ans:- False.
Non-metals can displace hydrogen from dilute acids.
Ans:-false
Ionic compounds conduct electricity whereas covalent compounds do not.
Ans:-true
Corrosion of requires moist air.
Ans:-true
The process of heating strongly sulphide ores in the presence of air is called roasting.
Ans:-true
What is an alloy
Ans:- An alloy is a homogeneous mixture of two or more metals (or a metal and small amounts of non-metal)
e.g. brass is an alloy of two metals: Cu and Zn
What do you understand by Malleability and ductility of a metal?
Ans:- The property which allows the metals to be hammered into thin sheets is called malleability. Gold and Silver metal are some of the best malleable metals. On the other hand, the property which allows the metals to be drawn into thin wires is called ductility. Gold is the most ductile metal.
Generally, all metals are good conductors of electricity, Which one is an exception?
Ans:- Exception Bi (Bismuth) and Pb (lead).
Which non-metal remain in a liquid state at normal temperature?
Ans:- Bromine (Br)
Which metal is liquid at normal temperature?
Ans:- Mercury (Hg)
What is metalloid?
Ans:- A metalloid is a chemical element with properties that are a mixture of both metals and non-metals. These metalloids are: Boron(B),Silicon (Si),Germanium (Ge), Arsenic (As),antimony(Sb),Tellurium (Te) and polonium(Po).
How many groups and periods are there in the periodic table?
Ans:- 18 groups and 7 periods.
Iron is more electropositive than Copper, how will you prove this?
Ans:- Iron atoms loss electrons readily to form positive ions. Hence it will be a very reactive metal whereas Copper atoms lose electrons less readily to form positive ions. By displacement reaction, when the iron is added to copper sulphate, the copper is displaced by the iron. This happens because iron is more reactive than copper.
What is the electrochemical series?
Ans:- electrochemical series is a series of electrodes arranged in order of their standard electrode potentials. The electrochemical series is also known as the activity series.
Arrange the following metals in decreasing order of their electrochemical series: Al, Fe, Pb, H, Cu, Pt.
Ans:- Al>Fe>Pb>H>Cu>Pt
Write one ore of Iron.
Ans:- Haematite (Fe2O3)
Write two metals which are purified by an electrolytic method.
Ans:- Cu, Zn, tin etc.
Write the name of two metals that can be obtained free in nature.
Ans:- Au (Gold) and Ag (Silver).
Name one ferrous alloy
Ans:- Stainless steel
Name one non-ferrous alloy
Ans:- Bronze since it does not contain Iron.
Name two methods used for Refining of metals.
Ans:- Electrolytic Refining, Zone Refining.
What is the basic difference between metal and non-metal?
Ans:- Basic difference between Metal and non-Metal are:-
1. Metals are a good conductor of heat and electricity but non-metals are a poor conductor of heat and electricity.
2. Metals form basic oxides whereas non-metals form acidic oxides or neutral oxides.
3. Metals are malleable and ductile and non-metals are brittle.
On which the reactivity of a metal depends?
Ans:- the reactivity of a metal depends on how easily it loses its valence electrons. If the electrons are lost easily, reactivity is more.
Though hydrogen is a non-metal it is kept in the electrochemical series why?
Ans:- This is due to the fact that like metals, hydrogen also loses electrons and forms positive ions H+.
Where is the place of metalloids in the periodic table?
Ans:- metalloids are placed between metals and non-metals of the periodic table.
Write the name and formula of a Halide ore.
Ans:- Horn silver (AgCl)
Write the name and formula of a Sulphide ore.
Ans:- ZnS (Zinc blende)
Give one reaction with an equation of metallic oxide which when dissolved in water produces an alkali.
Ans:- Sodium oxide is a basic oxide (mettalic oxide) which reacts with water to form alkali called sodium hydroxide.
Na2O(s) + H2O(l) —> 2NaOH (aq) {an alkali}
What is calcination?
Ans:- Calcination is the process in which a carbonate ore is heated strongly in absence of air to convert into metal oxide.e.g.
What is Roasting?
Roasting is the process in which a sulphide ore is strongly heated in the presence of air to convert it into metal oxide.
What is Carbon reduction process?
Ans:- The oxides of comparatively less reactive metal like zinc, iron, tin, lead and copper are usually reduced by using carbon as a reducing agent. Carbon reduces the metal oxide to free metal.e.g.
ZnO (s) + C (s) —->Zn (s) + CO (g).
Name two alloys of aluminium?
Ans:- Duralumin and Magnalium.
What is the use of stainless steel?
Ans:- stainless steel alloy is used for making household utensils.
Name one ore of mercury.
Ans:- Cinnabar (HgS).
What happens write in Chemical equation:
A piece of sodium is dipped in water
Ans:- Sodium reacts vigorously with cold water forming Sodium hydroxide and hydrogen gas.
2Na (s) + 2 H2O (l) —> 2NaOH (aq) + H2 (g) + Heat
Magnesium is treated with hydrochloric acid.
Ans:- Magnesium reacts quite rapidly with dilute hydrochloric acid to form magnesium chloride and hydrogen gas.
Mg (s) + 2 HCl (aq) —> MgCl2 (aq) + H2 (g)
A copper wire is dipped in AgNO3 solution.
Ans:- When copper wire is dipped in AgNO3 solution for some time, then it forms copper nitrate and silver metal.
2 AgNO3 (aq) + Cu (s) —> Cu(NO3 )2 (aq) + 2 Ag (s)
A Magnesium ribbon is burnt in the air
Ans:- Magnesium ribbon is burnt in the air to form basic oxide called magnesium oxide.
2 Mg (s) + O2 (g) —> 2 MgO (s)
Aluminium hydroxide is heated at a high temperature.
Ans:- On heating Aluminium hydroxide decomposes into aluminium oxide along with water.
2 Al(OH)3 —> Al2O3 + 3 H2O
What are different classes of alloys?
Ans:- The different classes of alloys are Brass, Bronze, Solder, amalgam, Stainless steel, Duralumin, magnalium and Steel.
Why is gold found in the free state in nature?
Ans:- gold found in the free state in nature because of low chemical reactivity.
Why are metals act as a reducing agent?
Ans:- metals act as a reducing agent because they have a tendency to denote electrons and get oxidised.
Write one name of an ore which is concentrated by froth floatation process.
Ans:- PbS (Galena).
Which of the following metals cannot produce hydrogen gas by reacting with water: Zn, Cu, Mg, Ca.
Ans:- Cu, since copper is less reactive than hydrogen.
What are metals?
Ans:- Metals are elements that conduct heat & electricity, malleable and ductile. e.g. Fe,Al,Cu,Ag,Zn,Pt etc.
Write the names of (a) liquid nonmetal (b) Solid non-metal.
Ans:- (a) Bromine (Br)
(b) Sulphur (s)
Can Al be obtained by carbon reduction process?
Ans:- No, Al metal is extracted by the electrolytic reduction.
Name the following:(i) One noble metal and the liquid metal
Ans:- noble metal: Ar(argon) liquid metal:Hg (mercury)
(ii) An oxide ore with its formula.
Ans:- bauxite (Al2O3 2H2O)
Write the name and chemical formula of one ore that can be purified by froth floatation process.
Ans:- Zinc blende (ZnS)
Which of the following metals cannot displace silver from an aqueous solution of silver nitrate: (a) Cu (b) Zn (c) Au (d) Fe.
Ans:- (c) Au, since Au is less reactive than Ag.
Write with balance chemical equation when (i) Steam is passed over a red hot iron.
Ans:- 3Fe (s) + 4H2O (g) —> Fe3O4 (s) + 4 H2 (g)
Name two elements which have both the properties of metal and non-metal.
Ans:- Boron & silicon, because of the metalloid.
Arrange the following metals in descending order of their reactivity Fe, Ag, Mg, Zn.
Ans:- Mg> Zn> Fe> Ag
Name two metals which are found in the free state in nature.
Ans:- Au (gold) & Pt (platinum)
Which of the following ores can be concentrated by the froth-flotation process? (a) Zinc blende ZnS (b) Horn Silver AgCl (c) Haematite Fe2O3(d) Bauxite Al2O3.2H2O
Ans:- (a) Zinc blende ZnS
Which metal is more metallic- sodium or aluminium and why?
Ans:- Sodium since sodium is more reactive than aluminium.
Aluminium is more reactive than iron, yet its corrosion is less than iron, why?
Ans:- Aluminium develops a protective layer of aluminium oxide by slowly reacting with oxygen present in the air whereas Iron cannot form a protective layer. So it easily gets corroded.
What do you understand by “thermite reaction?
Ans:- The reduction of a metal oxide to form metal by using aluminium powder as a reducing agent is called a thermite reaction.
Why is pure gold not suitable for making ornaments?
Ans:- Pure gold ( known as 24-carat gold ) is very soft due to which it is not suitable for making ornaments. So gold is alloyed with a small amount of Silver or Copper to make it hard.
Why are electrical wires coated with PVC?
Ans:- electrical wires coated with PVC (polyvinyl chloride) to prevent from electric shock since PVC does not conduct electricity.
Why is tungsten used almost exclusively for the filament of electric lamps?
Ans:- Tungsten is used almost exclusively for the filament of electric lamps because it has the lowest coefficient of thermal expansion, high melting point and its good tensile strength.
What is slag?
Ans:- The substance which is formed by reacting between “Gangue and Flux” is called slag.
Why is ZnO called an amphoteric oxide?
Ans:- ZnO (Zinc Oxide) is an amphoteric oxide because which reacts with acids as well as with bases to form salt and water.
Give reasons why copper is used to make hot water tanks but steel is not?
Ans:- This is because the iron (in steel) is more reactive than the copper. Iron reacts with hot steam to produce a ferrosoferric oxide, due to which body of the tank will become weaker to weaker but copper does not react with hot water.
Which alloy is used for making cattery?
Ans:- Lead alloy.
Short Type Questions: Marks: 2/3
A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y, and Z.
Ans:- A non-metal X is carbon because carbon exists in two different forms called allotropes of carbon. i.e. diamond and graphite. Y is diamond because diamond is the hardest natural substance. Z is graphite which is a good conductor of electricity.
A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH
Ans:- Metal A is aluminium which is used in thermite process. Al reacts with oxygen to form aluminium oxide (Al2O3) ‘B” which is amphoteric in nature.
The reaction of oxide B (Al2O3) with HCl:
Al2O3 (s) + 6 HCl (aq) —> 2 AlCl3 (aq) + 3 H2O (l)
The reaction of oxide B (Al2O3) with NaOH:
Al2O3 + 2 NaOH —> 2 NaAlO2 + H2O (l)
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Ans:- when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated because HNO3 is a strong oxidizing agent. So Nitric acid oxidizes this hydrogen to water.
The following reaction takes place when aluminium powder is heated with MnO
3MnO2 (s) + 4Al (s) —> 3Mn (I) + 2AL2O3 (l)+ Heat
(a) Is aluminium getting reduced? (b) Is MnO2 getting oxidized?
Ans:- (a) No, because oxygen is added to aluminum, therefore, it is getting oxidized.
(b) No, since Manganese has lost oxygen, therefore, it is getting reduced.
A solution of CuSO4 was kept in an iron pot. After a few days, the iron pot was found to have a number of holes in it. Expln the reason in terms of reactivity. Write the equation of reaction involved
Ans:-Iron is more reactive than copper. Iron displace copper from copper sulphate solution and forms iron sulphate, hence after a few days the iron pot was found to have a number of holes in it. The reaction involves in it :
Fe + CuSO4 (aq) —> FeSO4 (aq) + Cu
An alkali metal A gives a compound B ( molecular mass 40) on reacting with water. The compound B gives a soluble compound C on the treatment with aluminium oxide. Identify A, B, and C and give the reaction involved.
Ans:- A is Sodium (Na); B is Sodium hydroxide (NaOH); C is Sodium aluminate (NaAlO2). The reaction involves in it :
2 Na + 2 H2O —> 2 NaOH + H2 + heat.
Al2O3 + 2 NaOH —> 2 NaAlO2 + H2O.
Name the reaction on which activity series of metals is based? Name the most active metal and the least active metal in the activity series of metals.
Ans:-Displacement reaction. the most active metal- K(Potassium). least active metal-Au(Gold).
We can store copper sulphate in a silver vessel but not silver nitrate in a copper vessel. Explain why?
Ans:- We can store copper sulphate solution in a Silver vessel because Ag is less reactive than copper. In this case, no displacement reaction will take place. But on the other hand, Silver nitrate is not stored in a copper vessel because Cu is more reactive than Ag.
Why are metals electropositive and non-metals are electronegative?
Ans:- The tendency of metals to lose electrons in order to get stability is called the electropositive nature of metals. On the other hand, the tendency of non-metals to withdraw bonding electrons towards itself is called electronegative character.
Alternative answer:- Metals are electropositive because metal atoms lose electrons to form positive ions or cataions. e.g. Na, Mg, On the other hand, non-metals are electronegative because non-metal accept electrons to form negative ions or anions. e.g. F,Cl.
Discuss how the metallic properties changes in a group and period of the periodic table.
Ans:- On moving from left to right in a period, the metallic character of elements decreases but the non-metallic character increases. On going down in a group of the periodic table, the metallic character of elements increases.
Describe with an example how the electropositive and electronegative character changes in a group and period.
Ans:- On moving from left to right in a period, the electropositive character of elements decreases but the electronegative character increases. Thus in the 3rd period, Na is the most electropositive element whereas Cl is the most electronegative element. On going down in a group of the periodic table, the electropositive character of elements increases. In group 1 of the periodic table, Lithium is the least electropositive whereas Francium is the most electropositive element. On going down in a group of the periodic table, the electronegative character(non-metallic character) of elements decreases. e.g. When we go down in group 17 of the halogen elements, Fluorine is the most electronegative element whereas Iodine is the least electronegative element.
Write the distinguishing chemical properties of metals.
Ans:- The distinguishing chemical properties of metals:
1.Metal form a basic oxide.
2. Metal displace hydrogen from dilute acids.
3. Metal displace hydrogen from water (or steam)
4. Metal form ionic chlorides with chlorine.
Write with equation how copper reacts with water, chlorine, sulphur, and acid.
Ans:- Copper does not react with water since Cu is below hydrogen in reactivity series so it can not displace hydrogen from water.
Copper does not react with dilute HCl or dilute H2SO4 at all since Cu is less reactive than Hydrogen and can not displace hydrogen from dilute acid.
On heating, copper reacts with chlorine to form copper(ii) chloride:
Cu(s) + Cl2(g) —> CuCl2
Copper reacts with sulphur to form copper sulphide.
Cu + S —> CuS.
When Zinc rod is dipped in a blue solution of CuSO4, the blue color gradually disappears. What is the reason for this? In this reaction which one is oxidized and which one is reduced?
Ans:- When Zinc rod is dipped in CuSO4 Solution, then Zinc Sulphate solution and copper are obtained:
CuSO4 (aq) + Zn (s) —> ZnSO4 (aq) + Cu (s)
In this reaction, Zinc displaces copper from the copper sulphate compound since Zn is more reactive than Cu. The blue color CuSO4 solution fades due to the formation of ZnSO4 (colorless). It’s a displacement reaction. It is a redox reaction.
Zn is oxidized and Cu is reduced.
Copper is more reactive than silver, gold and platinum, prove with a chemical equation.
Ans:- Cu is more reactive than silver, gold, and platinum since silver, gold, and platinum are placed below Cu in the activity series. Equation:
2 AgNO3 (aq) + Cu (s) —> Cu(NO3)2 (aq) + 2 Ag (s)
Displacement reaction occurs because copper is more reactive than Silver (Ag).
Write one ore of the following metals: Ag, Au, Al, Cu.
Ans:- Ag: Argentite (Ag2S); Au: Calaverite (AuTe2); Al: Bauxite (Al2O32H2O); Cu: Cuprite (Cu2O).
What are the main steps in metal extraction’?
Ans:- The three major steps involved in the extraction of metal from its ore are : (1) Concentration of ore (2) Conversion of concentrated ore into metal (3) Refining of impure metal.
Give reasons: (a) All minerals are not ores.
Ans:- The natural materials in which the metals or their compounds are found in the earth are called minerals but those materials from which the metals can be extracted conveniently and profitably are called ores. Thus all minerals are not ore.
(b) Al cannot be extracted by carbon reduction process from its oxide.
Ans:- Al is so reactive that their oxides cannot be removed by using carbon as the reducing agent. The highly reactive metal Aluminium is extracted by the electrolysis of its molten Aluminium Oxide.
(c)The sulphide ores can be concentrated by Froths floatation process but oxide ores cannot.
Ans:- Sulphide ores being lighter ore easily wetted by pine oil to come on the surface of the solution with forths during froth floatation process leaving behind heavy matter of gangue wetted by water but oxide ores cannot be concentrated by this process.
What do you mean by Metallurgy? How an ore is concentrated by Froth floatation process?
Ans:-The various process involved in the extraction of metals from their ores, and refining are known as metallurgy.
The sulphide ores of copper, lead and zinc etc which are wetted by oils are concentrated by froth floatation process. In this process, the finely powdered ore is mixed with water and a suitable oil (e.g. Pine oil) in a large tank. The mixture is violently agitated by blowing air through the tank.
The oil froth containing the lighter ore particles come on to the surface while heavier impurities (not wetted by oils) sink down to the bottom.The froth containing the ore is removed by skimming off.
Write which of the following chemical equations are Gangue, Flux, and Slag:
3CaO + P2O5 —> Ca3(PO4)2 ; SiO2 + MgO —> MgSiO3
Ans:-3CaO(Gangue) + P2O5(Flux) —> Ca3(PO4)2(Slag)
SiO2 (Gangue)+ MgO(Flux) —> MgSiO3(Slag).
How are the impure metals purified by an electrolytic process? What is anode mud?
Ans:- Electrolytic refining: Electrolytic refining means refining by electrolysis. Many metals like copper, zinc, tin, lead chromium, nickel, silver and gold are refined electrolytically.
For the refining of an impure metal by electrolysis:(a) A thick block of the impure metal is made anode. (It is connected to the positive terminal of the battery).
(b) A thin strip of the pure metal is made cathode.(It is connected to the negative terminal of the battery).
(c) A water-soluble salt is taken as an electrolyte.
On passing electric current, impure metal dissolves from the anode and goes into the electrolyte solution and pure metal from the electrolyte deposits on the cathode. The soluble impurities present in the impure metal go into the solution whereas the insoluble impurities settle down at the bottom of the anode as ‘anode mud’.
How is Copper extracted by the electrolytic method? Write the reaction involved in the process.
Ans:- Electrolytic Refining of copper: The apparatus used for the electrolytic refining of copper has been shown in the figure.
Annode – impure copper (Cu); Cathode – pure copper (Cu); Electrolyte – acidified copper sulphate.
Allow the electric current to pass through it. Pure copper metal from the anode dissolves into the electrolyte and pure copper from the copper sulphate deposits on the cathode. Thus pure copper metal is produced on the cathode. The soluble impurities go into the solution whereas insoluble impurities collect below the anode as anode mud. The reaction involved in this process are:
At cathode: Cu2+ (copper ion from Electrolyte) + 2e– (Electrons from cathode) —> Cu (copper atom deposits on cathode)
At anode : Cu (copper atom from impure anode) – 2e– (electrons given to anode) —> Cu2+ (copper ion goes into electrolyte)
What is an alloy? Give an example. Why their anticorrosion property is very high?
Ans:- An alloy is a homogenous mixture of two or more metals (or metal and small amounts of non-metals). For example, Brass is an alloy of two metals: Cu and Zn.
Alloys are stronger than metals from which they are made and alloys are highly resistant to corrosion. So their anticorrosion property is very high.
Write the composition and use of Duralumin, Stainless Steel, Manganese Steel, and Brass.
Ans:- Duralumin: Al-95%, Cu – 4%, Mg – 0.5%, Mn – 0.5% Uses:Duralumin is used to make various parts of an aircrafts.
Stainless steel: iron – 73%, chromium – 18%, nickel – 8%, manganese – 0.035% +C. Uses: It is used for making household utensils.
Manganese Steel : Fe – 86%, Mn – 13% +C. Uses: It is used for making rock drills, safes etc.
Brass : Cu – 80% and Zn – 20%. Uses: It is used for making cooking utensils, screws, nut, bolts, wires etc.
What happens when an iron knife is dipped in CuSO4 solution?
Ans:- When an iron knife is dipped in CuSO4 solution, after some time we will see it has turned light green in color. Because iron from the knife displaces the copper from copper sulphate solution (since iron is more reactive than copper) and forms iron sulphate solution which is green in color and Cu metal.
CuSO4 [Copper(ii) sulphate] + Fe [iron grey]—> FeSO4 [greenish solution] + Cu [copper red brown]
What happens when a copper wire dipped in AgNO3 solution?
Ans:- When copper wire is dipped in AgNO3 solution for some time, the solution gradually becomes blue and a shining greyish-white deposit of silver metal is formed on copper wire.
2AgNO3 (aq) + Cu (s) —> Cu(NO3)2 (aq) + 2Ag (s).
In this reaction, Cu is more reactive than Ag. So Cu displaces silver from Silver nitrate solution and forms copper nitrate solution and silver metal.
Write two differences between metal and non-metal.
| Metals | Non-metals |
| 1) Metals are generally a good conductor of heat and electricity. | 1) Non- metals are poor conductor of heat and electricity. |
| 2) Metals from oxides which are basic in nature. | 2) Non- metals from oxide which are acidic in nature. |
Write the name of one alloy of iron and mention two of its uses.
Ans:- One alloy of iron is steel. When a small amount of carbon (0.1% – 0.5%) is mixed with iron, we get an alloy called steel which is hard and strong.
Uses: 1) It is used for making screws, nails, bridges and railway lines etc.
2) it is also used for the construction of buildings, vehicles and ship.
What happens to express in the chemical equation: a) Iron is burnt in air. b) Zinc sulphide is strongly heated in air.
Ans:- a) Iron metal does not burn in the air even on strong heating. Iron reacts with the oxygen of air on heating to form iron (II, III) oxide:
3Fe (s) + 2 O2 (g) —> Fe2O4 (S)
b) When zinc sulphide is strongly heated in air, it forms zinc oxide and sulphur dioxide.
2 ZnS + 3O2 —> 2 ZnO + 2 SO2
Balance the following equation: a) Sodium reacts with water to give hydrogen gas and sodium hydroxide. b) Iron reacts with dilute HCl to give hydrogen gas and ferric chloride. c) Copper displace Silver from Silver nitrate solution.
Ans:- A) 2 Na (s) + 2 H2O (l) —> 2 NaOH (aq) + H2 (g)
B) Fe (s) + 2 HCl (aq) —> FeCl2 (aq) + H2 (g)
C) Cu (s) + 2 AgNO3 (aq) —> Cu(NO3)2 (aq) + 2 Ag (s)
- (a) To prevent from rusting iron particles are galvanized.
(b)Na, K, ca and mg are alkali and alkaline earth metals. They are most reactive metal and readily react with most atmospheric oxygen and other gases .Therefore they are found in their free state in nature.
(c)When aluminum is dipped in nitric acid a layer of aluminum oxide is formed on the metal .This happens because nitric is a strong oxidizing agent. The layer of aluminum oxide prevents further reaction of aluminum. Due to this the reactivity of aluminum decreases. If it is dipped HNO
(d)The oxides of highly reactive metals like Na, mg is very stable and cannot be reduced by carbon as a reducing agent.
(e)This is because it dissociates into ions in its the aqueous state.
20.(a)The arrangement of metals in a vertical column in the order of decreasing reactivities is called reactivity series of metals or activity series of metals. The decreasing order of reactivity series are-:
Mg>Al>Zn>Fe>Cu
(b)(I)When we put zinc copper sulphate solution then the blue color of copper will fade.
(II)No change will be seen as copper is less reactive than iron.
(c)Sodium combines with hydrogen gas to give sodium hydride.
C.18.A- Sodium (Na), B-Chlorine (Cl),C-Sodium Chloride (Nacl),- hydrochloric acid(Hcl)
15.(a)Steps involved in the Extraction of less reactive metals like mercury:
(l)Roasting: Heating of metal sulphide in presence of excess of air to form metal oxide.
(ll)Reduction: Metal oxide can be reduced to metal in the presence of reducing agent at high temperature.
(b)Extraction of metals with medium reactivity like Zinc:
(l)Roasting: Heating of metal sulphide in the presence of excess of air to form metal oxide.
(ll)Reduction: Metal oxide can be reduced to metal in the presence of reducing agent like C or Al at high temperature.
- (6)Calcination in the process in which a carbonate are in heated strongly in the absence of air to convert it into metal oxide .
Carbonate ores are subjected to calcination.
Chemical Reaction:
- Since are A gives CO & B gives SO
So ores A is a carbonate ore and ore B is a sulphide ore.
As A is a Carbonate Ore, it is first subjected to calcination following by reduction.
As B is a sulphide ore, it is first subjected to calcination followed by reduction.
- The constituents of solder alloy are lead and tin. Solder alloy has a low melting point but has excellent electrical conductivity, So it is used for seldering of electrical wires.
46.(l) A->Carbon(C) ,B->Carbon monoxide(Co),C->Carbon dioxide( Co )
(ll)Since the electronic configuration of carbon is 2,4.It is present in 14th group of periodic table.
- The less reactive metals which are quite low in metal reactivity series are extracted by reduction of their oxides by heat alone.
Eg:-Extraction of mercury from cinnabar.
The moderately reactive metals which are in the middle of reactivity series are extracted by reduction of their oxides with Carbon, Aluminum, Sodium or Calcium.
The highly reactive metals (which are placed high up in the reactivity series) are extracted by electrolysis of their molten chlorides or oxides.Electrolylic reduction is borough about by passing electric current through the molten salt.
