CBSE Class 10 Science Metals and Non Metals Assignment Set 01

Question : In which of the following pair, both the substances are chemically same ?
(a) milk of lime and lime water
(b) dead burnt plaster and gypsum
(c) alumina and gypsum
(d) gypsum and plaster of paris
Answer : A

Question : Match the following -
Column ( A)                 Column (b)
(a) NaHCO₃               (i) Caustic soda
(b) Na2CO₃.10H₂O    (ii) Baking soda
(c) NaOH                  (iii) Blue vitriol
(d) CuSO₄.5H₂O       (iv) Washing soda
(a) (a) (i), (b) (ii), (c) (iii), (d) (iv)
(b) (a) (ii), (b) (iv), (c) (i), (d) (iii)
(c) (a) (i), (b) (iv), (c) (ii), (d) (iii)
(d) (a) (ii), (b) (iv), (c) (iii), (d) (ii)
Answer : B

Question : Chemical (a) is used for water softening to remove temporary hardness. (a) reacts with Na₂CO₃ to generate caustic soda. When CO₂ is bubbled through (a), it turns cloudy. What is the chemical formula of (a) ?
(a) CaCO₃
(b) CaO
(c) Ca(OH)₂
(d) Ca(HCO₃)₂
Answer : C

Question : Bleaching powder has strong bleaching action due to -
(a) chlorine
(b) nascent chlorine
(c) nascent oxygen
(d) Cl^–
Answer : B

Question : Dolomite is mineral whose formula is -
(a) CaCO₃
(b) MgCO₃
(c) CaCO₃.MgCO₃
(d) CaSO₄.2H₂O
Answer : C

Question : A solid compound ‘X’ on heating gives CO₂ gas and a residue. The residue mixed with water forms ‘Y’. On passing an excess of CO₂ through ‘Y’ in water, a clear solution ‘Z’ is obtained . On boiling ‘Z’. compound ‘X’ is reformed. The compound ‘X’ is -
(a) Ca(HCO₃)2
(b) CaCO₃
(c) Na2CO₃
(d) K2CO₃
Answer : B

Question : Which is not the correct process-mineral matching in metallurgical extraction.
(a) Leaching : silver
(b) Zone refining : lead.
(c) Liquation : tin
(d) Van Arkel : Zr
Answer : B

Question : Which of the following is not an ore of iron ?
(a) limonite
(b) cassiterite
(c) magnetite
(d) none of these
Answer : B

Question : In the extraction of copper from sulphide ore the metal is formed by reduction of Cu₂O with :
(a) FeS
(b) CO
(c) Cu₂S
(d) SO₂
Answer : C

Question : Which of the following is a carbonate ore ?
(a) pyrolusite
(b) malachite
(c) diaspore
(d) cassiterite
Answer : B

Question :  Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl₂ solution and aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃ solution and copper metal 
Answer :  D  

Question : Why do ionic compound have high melting points?
Answer :  Ionic compounds do not exist as single molecules but exist as aggregates of a large number of positive And negative ions due to strong electrostatic forces. Thus, large amount of energy is required to break The inter-ionic attraction, hence these have high melting points. 

Question : Using the electronic configuration, explain how magnesium atom combines with oxygen atom to form Magnesium oxide by transfer of electrons.
Answer :  Atomic no. of magnesium = 12

Question : What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical Reaction that takes place.
Answer :  Zinc is more reactive than iron. When zinc is added to a solution of iron (II) suphate, green color Of iron (II) sulphate fades out and iron metal is deposited)
Zn(s) + FeSO₄(aq) —–→ Fe(s) + ZnSO₄(aq) 

Question : What is meant by reactivity series of metals? State which of the following chemical reaction will takes Place giving suitable reason for each.
a) Zn + CuSO₄ ——→ ZnSO4 + Cu
b) Fe + ZnSO4 ——→ FeSO₄ + Zn
c) Zn + FeSO3 ——→ ZnSO₄ + Fe
Answer :  Reactivity series is a series of metals arranged in the order of their decreasing order of reactivity.
a) Reaction will take place because Zn is above Cu in the reactivity series and more reactive then Cu.
b) Reaction will not take place as Fe is below Zn in the reactivity series cannot displace Zn from its Solution. 

Question : Name the metal which is generally stored under kerosene and easily cut with knife.
Answer :  Sodium 

Question : Why does calcium float in water?
Answer :  It is because hydrogen gas formed which sticks to surface of calcium, therefore it floats. 

Question : Name the metal which reacts with a very dilute HNO₃ to evolve hydrogen gas.
Answer :  Magnesium. 

Question : A non-metal A is the largest constituent of air, when heated with H₂ in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence Of air it gives an acid D which acts as a strong oxidizing agent.
a) Identify A, B, C and D
b) To which group of periodic table does this non-metal belongs?
Answer :  a) A = N₂ Nitrogen
B = NH₃Amonia
C = NO Nitrogen
D = HNO₃ Nitric oxide
b) element A belongs to group 15 of the periodic table. Metal 

Question : How will you show that silver is less reactive than copper? 
Answer : In activity series silver is placed below the copper. hence copper is more reactive than silver

 

Question : i. Distinguish between ionic and covalent compounds under the following properties:

a. Strength of forces between constituent elements

b. Solubility of compounds in water

c. Electrical conduction in substances

ii. Explain how the following metals are obtained from their compounds by the reduction process:

a. Metal M which is in the middle of the reactivity series.

b. Metal N which is high up in the reactivity series. Give one example of each type.

Answer : i. a. Ionic compounds have strong force of attraction between the oppositely charged ions (e.g. Na⁺ and Cl^-), so they are solids. Covalent compounds have weak force of attraction between their molecules, so they are usually liquids or gases.

b. Ionic compounds are soluble in water but covalent compounds are insoluble in water.

c. Ionic compounds conduct electricity when dissolved in water or when melted because they contain ions (charged particles). But, covalent compounds like glucose do not conduct electricity because they do not contain ions.

ii. a. The metal M which is in the middle of the reactivity series (such as iron, zinc, lead, copper, etc.) is moderately reactive. So, for obtaining such metals from their compounds, their sulphides and carbonates (in which they are present in nature) are first converted into their oxides by the process of roasting and calcination respectively. For example, 

 

The metal oxide (MO) are then reduced to the corresponding metals by using suitable reducing agents such as carbon. For example, zinc metal from its oxide is obtained as follow:

 

b. The metal N which is high up in the reactivity series (such as sodium, magnesium, calcium, aluminium, etc.), is very reactive and cannot be obtained from its compound by heating with carbon.

Therefore, such metals are obtained by electrolytic reduction of their molten salt. For example, sodium is obtained by the electrolysis of molten sodium chloride (NaCl).

 

Question. Generally metals react with acids to give salt and hydrogen gas. Which of the given acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?
(a) H₂SO₄
(b) HCl
(c) HNO₃
(d) All the these
Answer : C

Question. Which of the following property is generally not shown by metals?
(a) Electrical conduction
(b) Sonorous
(c) Dullness
(d) Ductility
Answer : C

Question. A reactive metal can replace a _________ reactive metal, but a _______reactive one cannot replace a ________reactive metal from its salt solution.
Fill the blanks with respectively in given order.
(a) less, more, less, more
(b) less, less, more, more
(c) more, more, less, less
(d) more, less, less, more
Answer : D

Question. Which of the following are the allotropes of carbon?
(a) Diamond and graphite
(b) Turpentine and kerosene
(c) Glass and borosilicate
(d) Fullerene and Soil
Answer : A

Question. Which among the following statements is incorrect for magnesium metal?
(a) It burns in oxygen with a dazzling white flame
(b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas
(c) It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas
(d) It reacts with steam to form magnesium hydroxide and evolves hydrogen gas
Answer : B

Question. An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following
(a) Mg
(b) Na
(c) P
(d) Ca
Answer : B

Question. The ability of metals to be drawn into thin wire is known as
(a) ductility
(b) malleability
(c) sonorousity
(d) conducitivity
Answer : A

Question. An aluminium strip is kept immersed in a freshly prepared ferrous sulphate solution taken in a test tube, the change observed is that
(a) Green solution slowly gets decolourised with brown deposits.
(b) Lower end of the test tube becomes slightly warm
(c) A colourless gas with smell of burning sulphur is evolved
(d) Light green solution changes to blue
Answer : A

Question. Metallic oxide are generally _______in nature.
(a) Acidic
(b) Basic
(c) Neutral
(d) Amphoteric
Answer : B

Question. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)
Answer : D

Question. Which one among the following is an acidic oxide?
(a) Na2O
(b) CO
(c) CO₂
(d) Al₂O₃
Answer : C

Question. Phosphorous is a reactive _______________and it is stored in __________
(a) Metal, water
(b) Metal, kerosene
(c) Non-metal, water
(d) Non-metal, kerosene
Answer : C

Question. Which of the following gas gives limewater test?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Hydrogen
Answer : C

Question : A metal M readily forms water soluble sulphate MSO4 , water insoluble hydroxide M(OH)₂ and oxide MO which becomes inert on heating. The hydroxide is soluble in NaOH. The M is : 
a. Be
b. Mg
c. Ca
d. Sr
Answer : A

Question : The solubilities of carbonates decrease down the magnesium group due to a decrease in :
a. hydration energies of cations
b. inter ionic interaction
c. entropy of solution formation
d. lattice energies of solids.
Answer : A

Question : Several blocks of magnesium are fixed to the bottom of a ship to : 
a. make the ship lighter
b. prevent action of water and salt
c. prevent puncturing by under-sea rocks
d. keep away the sharks.
Answer : B

Question : One mole of magnesium nitride on the reaction with an excess of water gives :
a. one mole of ammonia
b. one mole of nitric acid
c. two moles of ammonia
d. two moles of nitric acid.
Answer : C

Question : Beryllium and aluminium exhibit many properties which are similar. But, the two elements differ in
a. exhibiting maximum covalency in compounds
b. forming polymeric hydrides
c. forming covalent halides
d. exhibiting amphoteric nature in their oxides.
Answer : A

Question : Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture ? 
a. The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic number down the group.
b. In both the alkali metals and the halogens the chemical reactivity decreases with increase in atomic number down the group.
c. Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens.
d. In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group.
Answer : D

Question : The ionic mobility of alkali metal ions in aqueous solution is maximum for : 
a. K⁺
b. Rb⁺
c. Li⁺
d. Na⁺
Answer : B

Question : Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides ?
a. Al₂O₃ < MgO < Na₂O < K₂O
b. MgO < K₂O < Al₂O₃ < Na₂O
c. Na₂O < K₂O < MgO < Al₂O₃
d. K₂O < Na₂O < Al₂O₃ < MgO
Answer : A

Question : The products obtained on heating LiNO₃ will be : 
a. Li₂O + NO₂ + O₂
b. Li₃N + O₂
c. Li₂O + NO + O₂
d. LiNO₃ + O₂
Answer : A

Question : Which of the following on thermal decomposition yields a basic as well as acidic oxide ?
a. NaNO₃
b. KClO₃
c. CaCO₃
d. NH₄NO₃
Answer : C

Question : Aluminium is extracted by the electrolysis of :
a. alumina
b. bauxite
c. molten cryolite.
d. alumina mixed with molten cryolite
Answer : D

Question : Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anomalous behaviour is that graphite : 
a. is a non-crystalline substance.
b. is an allotropic form of diamond.
c. has molecules of variable molecular masses like polymers.
d. has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.
Answer : D

Question : Heating an aqueous solution of aluminium chloride to dryness will give :
a. Al(OH)Cl₂
b. Al₂O₃
c. Al₂Cl₆
d. AlCl₃
Answer : B

Question : Refining of impure copper with zinc impurity is to be done by electrolysis using electrodes as :
Cathode Anode Cathode Anode
a. pure copper pure zinc
b. pure zinc pure copper
c. pure copper impure copper
d. pure zinc impure zinc
Answer : C

Question : Aluminium is extracted by the electrolysis of : 
a. alumina
b. bauxite
c. molten cryolite
d. alumina mixed with molten cryolite
Answer : D

Question : The metal extracted by leaching with a cyanide is :
a. Mg
b. Ag
c. Cu
d. Na
Answer : B

Question : Which one of the following ores is best concentrated by froth floatation method ? 
a. magnetite
b. cassiterite
c. galena
d. malachite.
Answer : C

Question : Heating mixture of Cu₂O and Cu₂S will give : 
a. Cu₂SO₃
b. CuO + CuS
c. Cu + SO₃
d. Cu + SO₂
Answer : D

Question : During the process of electro-refining of copper some metals present as impurity settle as anode mud.
These are : 
a. Sn and Ag
b. Pb and Zn
c. Ag and Au
d. Fe and Ni
Answer : C

Question : Which method of purification is represented by the following equation : 
Ti (s) + 2I₂(g) →523K  TiI4(g)  →1700K  Ti (s) + 2I₂(g)
a. Zone refining
b. Cupellation
c. Polling
d. Van Arkel
Answer : D

Question : In the context of the Hall - Heroult process for the extraction of Al, which of the following statements is false?
a. CO and CO₂ are produced in this process 
b. Al₂O₃ is mixed with CaF₂ which lowers the melting point of the mixture and brings conductivity
c. Al3+ is reduced at the cathode to form Al
d. Na₃AlF₆ serves as the electrolyte
Answer : D

Question : Which one of the following ores is best concentrated by froth floatation method?
a. Siderite
b. Galena
c. Malachite
d. Magnetite
Answer : B

Metals And Non-Metals Assertion Reason Class 10 Science  

A. Both assertion and reason are true, and reason is the correct explanation of assertion.
B. Both assertion and reason are true, but reason is not the correct explanation of assertion.
C. Assertion is true but reason is false.
D. Assertion is false and reason is true.

Question. Assertion: Copper displaces silver from silver nitrate solution.
Reason: Copper is more reactive than silver.

Answer: A

Question. Assertion: Aluminium oxide and zinc oxide are acidic in nature.
Reason: Amphoteric nature means that substance have both acidic and basic character.

Answer: C

Question. Assertion(A): Magnesium chloride is an ionic compound.
Reason (R): Metals and non-metals react by mutual transfer of electrons.

Answer: A

Question. Assertion (A): Hydrogen gas is not evolved when a metal reacts with nitric acid.
Reason (R): Nitric acid is a strong oxidising agent.

Answer: A

Question. Assertion(A): MgCl₂ is a covalent compound.
Reason (R): MgCl₂ is a good conductor of electricity in molten state.

Answer: D

Question. Assertion: Electrovalency of Na is +1.
Reason: The number of electrons which an atom either loses or gains in the formation of an ionic bond is known as its valency.

Answer: B

Question. Assertion: Different metals have different reactivities with water and dilute acids.
Reason: Reactivity of a metal depends on its position in the reactivity series.

Answer: B

Question. Assertion: The oxides of sulphur and phosphorus are acidic in nature.
Reason: Metal oxides are basic in nature.

Answer: B

Question. Assertion: Iron is the most widely used metal. But it is never used in its pure state.
Reason: Pure iron is very soft and stretches easily when hot.

Answer: A

1 Mark Questions :

Question : Name the following: 

i) The most abundant metal in the earth crust.

ii) The only non-metallic element which exists as a liquid.

iii) The process by which a metallic oxide ore changes into metal.

iv) Minerals which can be profitably converted to metals.

Short Answer type Questions :

Question. The bronze medals are made up of ?
Answer: copper and tin

Question. Name some metals which may corrode easily?
Answer: Iron, copper, silver

Question. Aluminium is a highly reactive metal, yet it is used to make utensils for cooking why
Answer: Good conductor of heat

Question. What chemical process is used for obtaining a metal from its oxide?
Answer: Reduction process

Question. What are minerals?
Answer: The elements or compounds, which occur naturally in the earth‘s crust are known as minerals.

Question. Name the alloy of lead and tin
Answer: Solder

Question. Define calcination.
Answer: The process of changing the carbonate ores and its oxides by heating strongly in limited air

Question. What are ores?
Answer: Minerals from which metals can be profitably extracted are called ores.

Question. Which gas is produced when Cinnabar is heated in the presence of oxygen?
Answer: SO2

Question. Name the metals at the top of the activity series
Answer: Potassium, sodium, calcium, magnesium and aluminium

Question : Show the electronic transfer in the formation of following :

i) Sodium oxide

ii) Calcium Hydride

ii) (Magnesium chloride ( At.Nos. Na=11 , O=8 , Ca=20 , H=1 , Mg=12 , Cl=17 )

Question : Classify the following compounds into ionic & molecular compounds.

( Fe₂O₃ , CO₂ , Mg₃N₃ , NH₃ , Li₂O , K₃N , HCl(g) , C₆H₁₂O₆ , ₃ , HCl (aq), CaO )

Question : Swasti took sulpher powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in the figure.

(a) What will be the action of gas on
(i) Dry litmus paper?
(ii) Moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place?
Answer :  (a) (i) no action on dry litmus paper (ii) moist litmus paper becomes re as the reaction taking place.
(b) Balanced equation for the reaction taking place:
         S + O₂ —-→ SO₂ 

Question : What is amphoteric oxide? Give examples.
Answer :  Those oxides which reacts with acids as well as bases to produce salts and water are called amphoteric Oxides. E.g. Na₂O, ZnO etc. 

Question : State reason for the following:
(i) Lemon is used for restoring the shine of tarnished copper vessels’
(ii) Copper wires are used in electrical connections.
Answer :  (i) when a copper object remains in damp air for a considerable time, the copper reacts slowly with Caron dioxide and water in air to form a green coating of basic copper carbonate on its surface. If corroded copper vessels are treated with lemon which is acidic in nature, the acid solution dissolves Green color basic copper carbonate and makes them look shiny.
(ii)Copper metal is the next best conductor of electricity after silver metal. So electric wires are made of copper.  

Question : Name a non-metal which is lustrous and a metal which is non-lustrous.
Answer :  Iodine is a non-metal which is lustrous and lead is a non-lustrous metal.  

 

ii. Formation of :

The atomic number of sodium is 11 and it has only one valence electron.

Hence, electronic configuration of is 2, 8, 1.

The atomic number of oxygen is ₈O and it has 6 electrons in its valence shell.

Hence, electronic configuration of is 2, 6.

Sodium has a tendency to lose the valence electron and oxygen has a tendency to gain the electron lost by sodium. Since, sodium can lose only one electron of the valence shell, and oxygen atom needs two electrons to complete its octet in the valence electron, two atoms of sodium combine with one atom of oxygen. By losing valence electron, sodium is changed into Na⁺ and by gaining two electrons lost by two sodium atoms, oxygen atom is changed into an oxide anion, . O₂ In this process , both the atoms, sodium and oxygen, obtain the stable electronic configuration of the noble gas neon.

 

 

It has 6 electrons in its valence shell. Therefore, it requires 2 more electrons to attain the stable electronic arrangement of neon gas. Thus, oxygen accepts 2 electrons donated by magnesium atom and forms a stable oxide ion, O^2-

MgO is ionic compound.

iii. The ions present in Na₂O are sodium ions (2Na⁺) and oxide ion O^2-.

The ions present in MgO are magnesium ion (Mg2+) and oxide ion O^2-.

HOTS: (High Order Thinking Skill) Questions with Answers:

Question 1. A metal acts as a good reducing agent. It reduces \(\text{Fe}_2\text{O}_3\) and \(\text{MnO}_2\). The reaction with \(\text{Fe}_2\text{O}_3\) is used for welding broken railway tracks. Identify the metal and write all the chemical reactions
Answer: The metal is Aluminium (\(\text{Al}\)).
Chemical reactions:
\(3\text{MnO}_2(s) + 4\text{Al}(s) \rightarrow 3\text{Mn}(l) + 2\text{Al}_2\text{O}_3(s) + \text{Heat}\)
\(\text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow 2\text{Fe}(l) + \text{Al}_2\text{O}_3(s) + \text{Heat}\)
In simple words: Aluminium reduces metal oxides to metals with the release of huge heat, which is used in thermite welding.

Exam Tip: Remember that Aluminium is a very reactive metal and acts as a strong reducing agent in thermite reactions.

Question 2. A yellow coloured powder 'X' is soluble in carbon disulphide. It burns with a blue flame forming suffocating smelling gas which turns moist blue litmus red. Identify 'X' and gives chemical reaction. Identify it is metal or nonmetal.
Answer: 'X' is Sulphur (\(\text{S}\)).
It is a non-metal.
Chemical reaction:
\(\text{S}(s) + \text{O}_2(g) \rightarrow \text{SO}_2(g)\)
In simple words: Sulphur is a yellow non-metal that dissolves in carbon disulphide and burns to form acidic sulphur dioxide gas.

Exam Tip: Solubility in carbon disulphide is a characteristic physical property of sulphur.

Question 3. An element reacts with oxygen to form an oxide which dissolves in dilute hydrochloric acid. The oxide formed also turns a solution of red litmus blue. Is the element a metal or non-metal? Explain with the help of a suitable example.
The element is a metal. When a metal reacts with oxygen, it forms a basic oxide. Basic oxides dissolve in acids to form salt and water, and they turn red litmus blue.
Answer: Example: Sodium (\(\text{Na}\))
\(4\text{Na}(s) + \text{O}_2(g) \rightarrow 2\text{Na}_2\text{O}(s)\)
\(\text{Na}_2\text{O}(s) + \text{H}_2\text{O}(l) \rightarrow 2\text{NaOH}(aq)\)
\(\text{Na}_2\text{O}(s) + 2\text{HCl}(dil) \rightarrow 2\text{NaCl}(aq) + \text{H}_2\text{O}(l)\)
In simple words: Metals form basic oxides which turn red litmus blue and react with acids.

Exam Tip: Metallic oxides are basic in nature, whereas non-metallic oxides are acidic in nature.

Question 4. A student set up an electric circuit as shown in Fig. He placed the metal to be tested in the circuit between terminals A and B as shown.
(i) Does the bulb glow? What does this indicate?
(ii) Why are electric wires coated with rubber like materials?
Answer: (i) Yes, the bulb glows. This indicates that metals are good conductors of electricity.
(ii) Rubber-like substances are insulators (bad conductors of electricity), which prevent electric shocks.
In simple words: Metals conduct electricity making the bulb glow, while rubber protects us from shocks.

Exam Tip: Metals have free electrons that allow electric current to pass through them easily.

Question 5. Royal water is prepared by mixing two acids 'A' and 'B'. It can dissolve gold and platinium. It is highly corrosive and fuming liquid. Identify 'A' and 'B'. What is the ratio in which 'A' and 'B' are mixed.
Answer: Acid 'A' is Concentrated Hydrochloric Acid (\(\text{HCl}\)) and Acid 'B' is Concentrated Nitric Acid (\(\text{HNO}_3\)).
They are mixed in the ratio of \(3 : 1\) by volume (\(3\text{HCl} : 1\text{HNO}_3\)).
In simple words: Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in a 3:1 ratio.

Exam Tip: Always specify that Aqua regia is a mixture of conc. \(\text{HCl}\) and conc. \(\text{HNO}_3\) in 3:1 ratio.

Question 6. Four metals A, B, C and D are, in turn, added to the following solutions one by one. The observations made are tabulated below:
Answer the following questions based on above information.
(i) Which is the most active metal and why?
(ii) What would be observed if B is added to a solution of copper (II) sulphate and Why?
(iii) Arrange the metals A, B, C and D in order of increasing reactivity.
(iv) Container of which metal can be used to store both zinc sulphate solution and silver nitrate solution.
(v) Which of the above solutions can be easily stored in a container made up of any of these metals?

Answer:
(i) Metal B is the most active metal because it displaces Iron from its salt solution.
(ii) Displacement reaction will take place, because B is more reactive than Cu.
(iii) Increasing order of reactivity: \(\text{D} < \text{C} < \text{A} < \text{B}\)
(iv) Metal D (since it does not react with any of the given salt solutions).
(v) \(\text{ZnSO}_4\)
In simple words: A more reactive metal displaces a less reactive metal from its salt solution.

Exam Tip: A metal can displace any metal below it in the reactivity series from its salt solution.

Question 7. Nikita took Zn, Al, Cu, Fe, Mg, Na metals & put each metal in cold water and then hot water. She reacted the metal with steam
(i) Name the metal which reacts with cold water.
(ii) Which of the above metals react with steam?
(iii) Name the metal which reacts with hot water.
(iv) Arrange these metals in order of increasing reactivity.
Answer: (i) Sodium (\(\text{Na}\))
(ii) Aluminium (\(\text{Al}\)), Zinc (\(\text{Zn}\)), Iron (\(\text{Fe}\))
(iii) Magnesium (\(\text{Mg}\))
(iv) Increasing order of reactivity: \(\text{Cu} < \text{Fe} < \text{Zn} < \text{Al} < \text{Mg} < \text{Na}\)
In simple words: Different metals show different reactivities towards water depending on their position in the reactivity series.

Question 8. A student was given Mg, Zn, Fe, and Cu metals. He put each of them in dil \(\text{HCl}\) contained in different test tubes. Identify which of them
(i) will not displace \(\text{H}_2\) from dil \(\text{HCl}\)
(ii) forms a pale green substance
(iii) will give \(\text{H}_2\) with \(5\%\) \(\text{HNO}_3\)
(iv) will be displaced from its salt solution by all other metals.
Answer: (i) Copper (\(\text{Cu}\))
(ii) Iron (\(\text{Fe}\))
(iii) Copper (\(\text{Cu}\))
(iv) Copper (\(\text{Cu}\))
In simple words: Less reactive metals like copper do not displace hydrogen from dilute acids.

Exam Tip: Metals placed below hydrogen in the reactivity series do not liberate hydrogen gas with dilute acids.

Question 9. A metal 'X' is found in the form of filings which burns vigorously when sprinkle on flame. When these filings are treated with sulphur a black coloured compound 'Y' is formed which is not attracted by magnet. 'X' reacts with dil \(\text{HCl}\) to liberate hydrogen gas. 'X' reacts with steam to form 'Z' along with hydrogen gas. Identify 'X', 'Y', and 'Z'. Write the reaction involved.
Answer: Metal 'X' is Iron (\(\text{Fe}\)).
Compound 'Y' is Iron (II) Sulphide (\(\text{FeS}\)).
Compound 'Z' is Magnetic Iron Oxide (\(\text{Fe}_3\text{O}_4\)).
Reactions involved:
\(\text{Fe}(s) + \text{S}(s) \xrightarrow{\text{Heat}} \text{FeS}(s)\)
\(\text{Fe}(s) + 2\text{HCl}(dil) \rightarrow \text{FeCl}_2(aq) + \text{H}_2(g)\)
\(3\text{Fe}(s) + 4\text{H}_2\text{O}(g) \rightarrow \text{Fe}_3\text{O}_4(s) + 4\text{H}_2(g)\)
In simple words: Iron reacts with sulphur to form iron sulphide and with steam to form magnetic oxide.

Exam Tip: Note that \(\text{FeS}\) is not attracted by a magnet in the same way as pure iron is, because its chemical nature is altered.

Question 10. A, B and C are 3 elements which undergo chemical reactions according to following equations:
a) \(\text{B}_2\text{O}_3 + 2\text{B} \rightarrow \text{B}_2\text{O}_3 + 2\text{A}\) (Note: balanced as given in source)
b) \(3\text{CSO}_4 + 2\text{B} \rightarrow \text{B}_2(\text{SO}_4)_3 + 3\text{C}\)
c) \(3\text{CO} + 2\text{A} \rightarrow \text{A}_2\text{SO}_3 + 3\text{C}\) (As per source data)
Answer of the following:
i) Which element is most reactive?
ii) Which element is least reactive?
Answer: i) Most reactive element is B as it has replaced both A and C from their compounds.
ii) Element C is least reactive as it has been replaced by both A and B.
In simple words: The element that displaces others is the most reactive, and the one that gets displaced by all is the least reactive.

Exam Tip: Displacement reactions are direct indicators of the relative reactivities of elements.

Question 11. An element X on reacting with \(\text{O}_2\) forms \(\text{X}_2\text{O}\).This Oxide dissolves in water and turns blue litmus paper red. Predict the nature of element whether it is a metal or a non metal.
Answer: The oxide is acidic in nature as it has turned blue litmus to red. Hence X is a non-metal.
In simple words: Non-metallic oxides are acidic and turn blue litmus red.

Exam Tip: Remember: Acidic oxides turn blue litmus red; basic oxides turn red litmus blue.

Question 12. An element E combines with \(\text{O}_2\) to form an oxide \(\text{E}_2\text{O}\), which is a good conductor of electricity. Answer the following:
i) How many electrons will be present in the outer most shell of E?
ii) Write the formula of the compound formed when it combines with Chlorine.
Answer: i) Valency of element E is 1. This means it has only one electron in the valence shell.
ii) Valency of Chlorine is 1 and Valency of E is also 1. Therefore the formula will be \(\text{ECl}\).
In simple words: Since E forms \(\text{E}_2\text{O}\), its valency is 1, so with chlorine it forms ECl.

Exam Tip: Elements with 1 valence electron are monovalent alkali metals.

MORE QUESTIONS FOR PRACTICE

Q1. Name 2 metals which are neither ductile nor malleable.
Answer: Mercury and Gallium (or Zinc in certain solid conditions, but typically brittle metals like antimony/bismuth or liquid mercury).
In simple words: Some metals lack the typical physical properties of ductility and malleability.

Exam Tip: Mercury is liquid at room temperature and cannot be drawn into wires or sheets.

Q2. What happens to the electrical conductivity of a metal when it is heated?
Answer: The electrical conductivity of a metal decreases when it is heated because thermal vibrations of ions disrupt the smooth flow of electrons.
In simple words: Heating a metal increases resistance and decreases its conductivity.

Exam Tip: Unlike semiconductors, pure metals show a decrease in conductivity with an increase in temperature.

Q3. What is the nature of \(\text{Al}_2\text{O}_3\)?
Answer: \(\text{Al}_2\text{O}_3\) is amphoteric in nature, meaning it reacts with both acids and bases to form salt and water.
In simple words: Amphoteric oxides show both acidic and basic properties.

Q4. An alloy of a metal contains Mercury. What will you call it?
Answer: An amalgam.
In simple words: Alloys containing mercury are known as amalgams.

Exam Tip: Sodium amalgam and zinc amalgam are common examples used in laboratories.

Q5. What is the purpose of adding C to molten Iron?
Answer: Carbon is added to molten iron to make it hard and strong, converting it into steel.
In simple words: Adding a small amount of carbon makes iron much stronger and less brittle.

Exam Tip: Pure iron is very soft and stretches easily; carbon adds structural strength.

Q6. Who am I?
a) Versatility is my name. There are more than 5 million compounds of me.
b) Your teacher uses me, I am a metallic element found in chalk, limestone, marble etc.
c) Shocking? In one form I am a conductor whereas in another an insulator.
d) 'Bang'. I am the element formed when \(\text{H}_2\) bomb explodes.
Answer: a) Carbon
b) Calcium
c) Carbon (Graphite is a conductor, Diamond is an insulator)
d) Helium (formed by nuclear fusion)
In simple words: These riddles test key chemical elements and their allotropes.

Exam Tip: Graphite's free electrons make it conduct electricity, unlike diamond.

Q7. Which of the following is metal and non metal?
\(^7_3\text{X}, ^3_1\text{Y}, ^{10}_9\text{Z}\)
Answer:
Atomic number 3 (\(^7_3\text{X}\)) is Lithium (Metal).
Atomic number 1 (\(^3_1\text{Y}\)) is Hydrogen (Non-metal).
Atomic number 9 (\(^{10}_9\text{Z}\)) is Fluorine (Non-metal).
In simple words: Elements with 1, 2, or 3 valence electrons are generally metals, while those with 5, 6, or 7 are non-metals.

Exam Tip: Use atomic numbers to write electronic configurations and determine metal/non-metal character.

Q8. Name one metal and one non metal element which are obtained on a large scale from sea water.
Answer: Metal: Sodium (obtained from sodium chloride present in sea water).
Non-metal: Chlorine (obtained by the electrolysis of brine/sea water).
In simple words: Sodium chloride from sea water is the primary source of sodium and chlorine.

Exam Tip: Electrolysis of aqueous sodium chloride (brine) produces chlorine gas at the anode.

Q9. Zn is more electropositive than Fe. So it should get corroded faster than Fe. But it does not happen. Instead it is used to galvanize Iron. Explain why does it happen so?
Answer: When zinc is coated on iron, it forms a protective zinc oxide layer on the surface. Even if the coating is broken, zinc preferentially oxidizes (corrodes) instead of iron because it is more reactive, thus sacrificing itself to protect iron (sacrificial protection).
In simple words: Zinc corrodes in place of iron, saving the iron from rusting.

Exam Tip: This process of protecting iron by coating with a more reactive metal is called sacrificial protection or galvanization.

Q10. The reaction of a metal X with \(\text{Fe}_2\text{O}_3\) is highly exothermic and is used to join railway tracks. Identify metal X. Write the chemical equation of its reaction with \(\text{Fe}_2\text{O}_3\).
Answer: Metal X is Aluminium (\(\text{Al}\)).
Chemical equation:
\(\text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow 2\text{Fe}(l) + \text{Al}_2\text{O}_3(s) + \text{Heat}\)
In simple words: Aluminium reduces iron oxide to molten iron in the thermite reaction.

Exam Tip: The immense heat produced melts the iron, which fills the cracks in railway tracks.

Q11. Why do metals generally not evolve \(\text{H}_2\) gas when reacted with \(\text{HNO}_3\)? Name 2 metals which liberate \(\text{H}_2\) gas with very dil. \(\text{HNO}_3\).
Answer: Nitric acid is a strong oxidizing agent. It oxidizes the hydrogen gas produced to water and itself gets reduced to nitrogen oxides. However, Magnesium (\(\text{Mg}\)) and Manganese (\(\text{Mn}\)) react with very dilute nitric acid to evolve hydrogen gas.
In simple words: Nitric acid turns hydrogen into water, except with very dilute acid and specific metals like Mg and Mn.

Q12. Name one metal each which is extracted by:
a) reduction with heat alone
b) reduction with C
c) reduction with Al.
d) electrolytic reduction.
Answer: a) Mercury (\(\text{Hg}\)) from cinnabar
b) Zinc (\(\text{Zn}\)) or Iron (\{ \text{Fe} \)
c) Manganese (\(\text{Mn}\)) or Chromium (\(\text{Cr}\))
d) Sodium (\(\text{Na}\)) or Aluminium (\(\text{Al}\))
In simple words: Different methods of reduction are used based on the reactivity of the metals.

Exam Tip: Highly reactive metals use electrolysis, moderately reactive use carbon reduction, and least reactive use thermal decomposition.

Q13. a) A metal M is found in nature as \(\text{MCO}_3\). It is used in galvanizing Fe articles. Name the Metal M.
b) How can metal M be obtained from its Carbonate Ore?
Answer: a) Metal M is Zinc (\(\text{Zn}\)).
b) It is obtained by calcination followed by reduction with carbon:
\(\text{ZnCO}_3(s) \xrightarrow{\text{Heat}} \text{ZnO}(s) + \text{CO}_2(g)\) (Calcination)
\(\text{ZnO}(s) + \text{C}(s) \rightarrow \text{Zn}(s) + \text{CO}(g)\) (Reduction)
In simple words: Carbonate ores are heated strongly in the absence of air (calcination) to form oxides, which are then reduced.

Exam Tip: Calcination is heating in the absence of air, while roasting is heating in the presence of excess air.

Q14. Explain how the following metals are obtained from their compounds by the reduction process.
a) Metal X which is low in the reactivity series.
b) Metal Y in the middle of reactivity series.
c) Metal Z which is high in the reactivity series.
Give an eg of each.
Answer: a) By heating their sulphide ores in air (Roasting). Example: Mercury from Cinnabar (\(\text{HgS}\)).
b) By reducing their oxide ores with carbon. Example: Zinc from Zinc Oxide (\(\text{ZnO}\)).
c) By electrolytic reduction of their molten chlorides or oxides. Example: Aluminium from Alumina (\(\text{Al}_2\text{O}_3\)).
In simple words: Extraction method depends directly on metal reactivity.

Exam Tip: Highly reactive metals cannot be reduced by carbon because they have a greater affinity for oxygen than carbon does.

Q15. Write the equations for the reactions of:
a) Iron with Steam
b) Calcium with Water.
c) Potassium with Water.
Answer: a) \(3\text{Fe}(s) + 4\text{H}_2\text{O}(g) \rightarrow \text{Fe}_3\text{O}_4(s) + 4\text{H}_2(g)\)
b) \(\text{Ca}(s) + 2\text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(aq) + \text{H}_2(g)\)
c) \(2\text{K}(s) + 2\text{H}_2\text{O}(l) \rightarrow 2\text{KOH}(aq) + \text{H}_2(g) + \text{Heat}\)
In simple words: Metals react with water to form metal hydroxides (or oxides) and hydrogen gas.

Q16. Why Al metal cannot be obtained by the reduction of \(\text{Al}_2\text{O}_3\) with Coke.
Answer: Aluminium has a very high affinity for oxygen, which is greater than that of carbon. Therefore, carbon cannot reduce aluminium oxide to aluminium.
In simple words: Aluminium loves oxygen more than carbon does, so carbon cannot pull oxygen away from it.

Exam Tip: Electrolytic reduction is mandatory for highly reactive metals like Al, Na, and Mg.

Q17. You cannot hold a piece of Na in your hand but you can eat Na ions in NaCl. Why?
Answer: Metallic sodium is extremely reactive and catches fire in moisture, causing severe burns. However, sodium ions (\(\text{Na}^+\)) in sodium chloride (\(\text{NaCl}\)) are stable because they have achieved a stable octet electronic configuration.
In simple words: Metallic sodium is dangerous and reactive, but sodium ions in salt are stable and harmless.

Exam Tip: Chemical properties of ions differ completely from their neutral atoms due to stable valence shells.

Q18. Cinnabar is an ore of metal X. It exists in the lower order of the reactivity series. Write down the reaction involved in it for the extraction of X.
Answer: Metal X is Mercury (\(\text{Hg}\)).
Reactions:
\(2\text{HgS}(s) + 3\text{O}_2(g) \xrightarrow{\text{Heat}} 2\text{HgO}(s) + 2\text{SO}_2(g)\)
\(2\text{HgO}(s) \xrightarrow{\text{Heat}} 2\text{Hg}(l) + \text{O}_2(g)\)
In simple words: Cinnabar is roasted to mercuric oxide, which is then thermally decomposed to pure mercury.

Exam Tip: Roasting sulphide ores of less reactive metals directly yields the metal oxide or metal upon heating.

Q19. Identify the acid which oxidizes \(\text{H}_2\) to \(\text{H}_2\text{O}\).
Answer: Nitric acid (\(\text{HNO}_3\)).
In simple words: Nitric acid is a powerful oxidizing agent that converts hydrogen into water.

Exam Tip: Because of its strong oxidizing action, \(\text{HNO}_3\) prevents hydrogen gas evolution with most metals.