Class 10 Science · Chapter 3

Metals and Non-metals

344 Class 10 Science questions on Metals and Non-metals from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 9 of 18

1. Q161 CBSE 2025
   Oxides ​of ​aluminium ​and zinc ​are :

   1. (a)Acidic
   2. (b)Amphoteric
   3. (c)Basic
   4. (d)Neutral
   Show answer

   (b) Amphoteric

   Step-by-step solution →
2. Q162 CBSE 2025
   The ​metals ​obtained from their ​molten ​chlorides ​by the ​process of ​electrolytic reduction ​are :

   1. (a)Gold and silver
   2. (b)Calcium and magnesium
   3. (c)Aluminium and silver
   4. (d)Sodium and iron
   Show answer

   (b) Calcium and magnesium

   Step-by-step solution →
3. Q163 CBSE 2025
   During electrolytic refining of ​copper, ​the anode, the ​cathode and the ​electrolyte ​used respectively are

   1. (a)Impure copper, pure copper, acidified copper sulphate solution
   2. (b)Pure copper, impure copper, sulphuric acid
   3. (c)Pure copper, impure copper, acidified copper sulphate solution
   4. (d)Impure copper, pure copper, distilled water
   Show answer

   (a) Impure copper, pure copper, acidified copper sulphate solution

   Step-by-step solution →
4. Q164 CBSE 2025
   The ​formation ​of ​magnesium ​oxide ​is ​correctly shown in option ​:

   1. (a)One $\text{Mg}$ atom transfers both of its outer electrons to a single $\text{O}$ atom, giving ${\text{Mg}}^{2+}$ and one oxide ion with a complete octet, written $[\text{O}{]}^{2-}$.
   2. (b)One $\text{Mg}$ atom transfers a single electron to one $\text{O}$ atom, giving ${\text{Mg}}^{+}$ and one $[\text{O}{]}^{-}$ ion.
   3. (c)One $\text{Mg}$ atom transfers one electron to each of two $\text{O}$ atoms, giving ${\text{Mg}}^{2+}$ and two $[\text{O}{]}^{-}$ ions, written $[\text{O}{]}_2^{-}$.
   4. (d)Two $\text{Mg}$ atoms transfer electrons to a single $\text{O}$ atom, giving $[{\text{Mg}}^{2+}{]}_2$ and one $[\text{O}{]}^{2-}$ ion.
   Show answer

   (a) One $\text{Mg}$ atom transfers both of its outer electrons to a single $\text{O}$ atom, giving ${\text{Mg}}^{2+}$ and one oxide ion with a complete octet, written $[\text{O}{]}^{2-}$.

   Step-by-step solution →
5. Q165 CBSE 2025
   Two ​statements are given ​— one labelled as Assertion (A) and the other labelled ​as Reason ​(R). Select ​the correct ​answer from the codes given below.

   Assertion (A): The metals high up in the reactivity series cannot be obtained from their compounds by heating with carbon.

   Reason (R): Displacement reactions can also be used to obtain metal.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true, but Reason (R) is false.
   4. (d)Assertion (A) is false, but Reason (R) is true.
   Show answer

   (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

   Step-by-step solution →
6. Q166 CBSE 2025
   Two ​statements are ​given below — one labelled as ​Assertion (A) ​and the other labelled as Reason (R). Select the ​correct ​answer to this question from the codes (a), (b), ​(c) and (d) given below.

   Assertion (A): Hydrogen gas is not evolved when a metal reacts with nitric acid.

   Reason (R): Nitric acid is a strong reducing agent and reduces the hydrogen produced in the reaction to water.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true, but Reason (R) is false.
   4. (d)Assertion (A) is false, but Reason (R) is true.
   Show answer

   (c) Assertion (A) is true, but Reason (R) is false.

   Step-by-step solution →
7. Q167 CBSE 2025
   Two ​statements ​are given — one labelled as Assertion (A) and ​the ​other labelled as Reason ​(R). Select the correct answer to ​this question from the codes (a), (b), (c) ​and ​(d) as given below.

   Assertion (A): Ductility is that property of metals which enables copper to be used in making cooking utensils.

   Reason (R): Copper is a metal which is ductile as well as malleable.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true, but Reason (R) is false.
   4. (d)Assertion (A) is false, but Reason (R) is true.
   Show answer

   (d) Assertion (A) is false, but Reason (R) is true.

   Step-by-step solution →
8. Q168 CBSE 2025
   Two statements are given — one labelled as Assertion ​(A) and the other ​labelled ​as ​Reason (R). Select the ​correct ​answer to this ​question from ​the codes (a), (b), (c) and (d) as given below.

   Assertion (A): Brass is prepared by first melting copper and then dissolving tin into it in a definite proportion.

   Reason (R): The primary metal of brass is copper.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true, but Reason (R) is false.
   4. (d)Assertion (A) is false, but Reason (R) is true.
   Show answer

   (d) Assertion (A) is false, but Reason (R) is true.

   Step-by-step solution →
9. Q169 CBSE 2025
   1. (a)In common ​practice silver is recovered from silver nitrate solution by the use ​of copper metal. ​Name the type of ​reaction that takes place in this process ​and ​give the chemical equation of the reaction involved.
   2. (b)Name the method ​used for refining silver.
   Show answer

   It is a displacement reaction, $\text{Cu}+2{\text{AgNO}}_3\to {\text{Cu(NO}}_3{)}_2+2\text{Ag}$; silver is refined by electrolytic refining.

   (a) It is a displacement reaction (copper, being more reactive, displaces silver from its salt): $\text{Cu (s)}+2{\text{AgNO}}_3\text{ (aq)}\to {\text{Cu(NO}}_3{\text{)}}_2\text{ (aq)}+2\text{Ag (s)}$; (b) Silver is refined by electrolytic refining.

   Step-by-step solution →
10. Q170 CBSE 2025
    A ​light ​green coloured solution of sulphate salt of metal 'P' is taken in a beaker, a rod of another ​metal ​'Q' is put in ​this solution as shown the following figures : Identify ​the metals 'P' and ​'Q' and write its chemical equation for the reaction that occurs. State ​the conclusion of this reaction in terms of reactivity series of metals.

    Show answer

    P is iron and Q is zinc; zinc displaces iron from its salt solution, so zinc is more reactive than iron.

    P is iron (Fe), whose sulphate ${\text{FeSO}}_4$ gives the light green solution, and Q is zinc (Zn), whose sulphate ${\text{ZnSO}}_4$ is colourless. The reaction is $\text{Zn(s)}+{\text{FeSO}}_4\text{(aq)}\to {\text{ZnSO}}_4\text{(aq)}+\text{Fe(s)}$. Conclusion: zinc displaces iron from its salt solution, so zinc is more reactive than iron and lies above it in the reactivity series — a more reactive metal displaces a less reactive one from its salt solution.

    Step-by-step solution →
11. Q171 CBSE 2025
    Cinnabar is an ore of a metal ‘X’. When this ore is heated in air, ​it is first converted into oxide of ‘X’ (XO) and then reduced to metal ‘X’ ​on further heating. Identify ​metal ‘X’ ​and write chemical equations for the reactions that ​occur ​in the ​above ​processes.
    Show answer

    X is mercury: roasting cinnabar gives mercury oxide and sulphur dioxide, and heating the oxide further gives mercury and oxygen.

    Metal X is mercury (Hg); cinnabar is mercury(II) sulphide, $\text{HgS}$, and XO is mercury(II) oxide, $\text{HgO}$. Heating the ore in air (roasting): $2\text{HgS}(\text{s})+3{\text{O}}_2(\text{g})\stackrel{\text{heat}}{\to }2\text{HgO}(\text{s})+2{\text{SO}}_2(\text{g})$ Further heating of the oxide: $2\text{HgO}(\text{s})\stackrel{\text{heat}}{\to }2\text{Hg}(\text{l})+{\text{O}}_2(\text{g})$

    Step-by-step solution →
12. Q172 CBSE 2025
    Name a metal found in ​the earth’s ​crust

    1. (i)in ​free state and
    2. (ii)​in the form of its compound. State where each of these ​metals are placed in ​the ​reactivity series of metals.
    Show answer

    Gold is found free and lies at the bottom of the reactivity series; sodium is found as compounds and lies near the top.

    (i) Gold is found in the free state. It is placed at the bottom of the reactivity series, being the least reactive metal in it. (ii) Sodium is found only in the form of its compounds, such as sodium chloride. It is placed at the top of the reactivity series, just below potassium, being highly reactive.

    Step-by-step solution →
13. Q173 CBSE 2025
    1. (i)What ​is an ​alloy ?
    2. (ii)Write ​the composition ​of solder and the property ​which makes it suitable ​for ​welding electric ​wires.
    Show answer

    An alloy is a homogeneous mixture of metals; solder is lead and tin, and its low melting point suits welding wires.

    (i) An alloy is a homogeneous mixture of two or more metals, or of a metal and a non-metal. (ii) Solder is an alloy of lead and tin taken in roughly equal amounts, about $50\%$ Pb and $50\%$ Sn; its very low melting point — lower than that of either lead or tin — is the property that makes it suitable for welding electric wires.

    Step-by-step solution →
14. Q174 CBSE 2025
    Show ​the formation of magnesium chloride ​by electron transfer. Write the ​name of the cation ​and ​anion present in the ​compound formed. ​(Atomic Number ​of Mg $=12$, Cl $=17$)
    Show answer

    Magnesium gives two electrons to two chlorine atoms, forming ${\text{Mg}}^{2+}$ (cation) and ${\text{Cl}}^{-}$ (anion) in ${\text{MgCl}}_2$.

    Magnesium ($2,8,2$) loses its two outer electrons to give ${\text{Mg}}^{2+}$ ($2,8$), and each of two chlorine atoms ($2,8,7$) gains one to give ${\text{Cl}}^{-}$ ($2,8,8$), so ${\text{Mg}}^{2+}+2{\text{Cl}}^{-}\to {\text{MgCl}}_2$. The cation present is the magnesium ion, ${\text{Mg}}^{2+}$, and the anion is the chloride ion, ${\text{Cl}}^{-}$.

    Step-by-step solution →
15. Q175 CBSE 2025
    Show the ​formation ​of calcium chloride by the transfer of ​electrons from one element to the other. Atomic ​Number of calcium ​and ​chlorine is 20 and 17 respectively.
    Show answer

    Calcium gives one electron to each of two chlorine atoms, forming ${\text{Ca}}^{2+}$ and two ${\text{Cl}}^{-}$ ions that attract to give ${\text{CaCl}}_2$.

    Calcium ($2,8,8,2$) gives its two outermost electrons, one to each of two chlorine atoms ($2,8,7$): $\text{Ca}\to {\text{Ca}}^{2+}+2e^{-}$ and $2\text{Cl}+2e^{-}\to 2{\text{Cl}}^{-}$. Both ions then have the octet $2,8,8$, and the oppositely charged ions attract to form calcium chloride: ${\text{Ca}}^{2+}+2{\text{Cl}}^{-}\to {\text{CaCl}}_2$.

    Step-by-step solution →
16. Q176 CBSE 2025
    During electrolytic refining of silver :

    1. (i)What are the electrodes – cathode and ​anode ​made up of ?
    2. (ii)​What is ​anode ​mud ? ​Why is it called ​so ​?
    Show answer

    Anode is impure silver and cathode is pure silver; anode mud is the insoluble noble-metal impurity that settles below the anode.

    (i) The anode is a thick block of impure silver and the cathode is a thin strip of pure silver, dipped in a solution of a silver salt such as acidified silver nitrate. (ii) Anode mud is the insoluble impurities — noble metals such as gold and platinum — which do not dissolve in the electrolyte and settle down at the bottom, just below the anode; it is called anode mud because it collects beneath the anode as a mud-like deposit.

    Step-by-step solution →
17. Q177 CBSE 2025
    How ​is zinc extracted from ​its ore? ​Name the processes involved ​in the ​extraction and write ​chemical equations for the reactions ​that occur ​during these processes.
    Show answer

    Zinc ore is converted to zinc oxide by roasting or calcination, and the oxide is reduced with carbon.

    Zinc is a metal of the middle of the reactivity series, so its ore is first converted into zinc oxide and the oxide is then reduced with carbon. The processes are: (i) **Roasting** of the sulphide ore zinc blende — $2\text{ZnS}+3{\text{O}}_2\stackrel{\text{heat}}{\to }2\text{ZnO}+2{\text{SO}}_2$; (ii) **Calcination** of the carbonate ore calamine — ${\text{ZnCO}}_3\stackrel{\text{heat}}{\to }\text{ZnO}+{\text{CO}}_2$; (iii) **Reduction** of the oxide with carbon — $\text{ZnO}+\text{C}\stackrel{\text{heat}}{\to }\text{Zn}+\text{CO}$. The impure zinc is finally purified by electrolytic refining.

    Step-by-step solution →
18. Q178 CBSE 2025
    “Aluminium oxide is an amphoteric oxide.” ​Justify ​this ​statement ​giving ​chemical ​equation for ​the ​reactions involved.
    Show answer

    Aluminium oxide reacts with both an acid and a base to give a salt and water, so it is amphoteric.

    An amphoteric oxide reacts with both acids and bases to give a salt and water. Aluminium oxide does both: with hydrochloric acid it behaves as a base, ${\text{Al}}_2{\text{O}}_3+6\text{HCl}\to 2{\text{AlCl}}_3+3{\text{H}}_2\text{O}$, and with sodium hydroxide it behaves as an acid, ${\text{Al}}_2{\text{O}}_3+2\text{NaOH}\to 2{\text{NaAlO}}_2+{\text{H}}_2\text{O}$ (sodium aluminate). So aluminium oxide is an amphoteric oxide.

    Step-by-step solution →
19. Q179 CBSE 2025
    1. (a)“Displacement reactions also play a key role in extracting metals in the middle of ​the ​reactivity series.” Justify this ​statement with ​two examples.
    2. (b)Why can metals high up in the reactivity ​series not ​be obtained by reduction ​of their oxides by ​carbon ?
    Show answer

    Aluminium displaces middle-of-series metals such as iron and manganese from their oxides; carbon cannot reduce the oxides of highly reactive metals.

    (a) Metals of medium reactivity ($\text{Zn}$, $\text{Fe}$, $\text{Pb}$, $\text{Cu}$) are freed from their oxides by a **more** reactive metal, which displaces them; these displacement reactions are highly exothermic. Examples: ${\text{Fe}}_2{\text{O}}_3+2\text{Al}\to 2\text{Fe}+{\text{Al}}_2{\text{O}}_3+\text{heat}$ (the thermit reaction, used to weld broken rails) and $3{\text{MnO}}_2+4\text{Al}\to 3\text{Mn}+2{\text{Al}}_2{\text{O}}_3+\text{heat}$. (b) Metals high up in the series ($\text{K}$, $\text{Na}$, $\text{Ca}$, $\text{Mg}$, $\text{Al}$) have a far greater affinity for oxygen than carbon has, so their oxides are too stable for carbon to reduce — these metals are themselves stronger reducing agents than carbon. They are therefore obtained by electrolytic reduction of their molten chlorides or oxides.

    Step-by-step solution →
20. Q180 CBSE 2025
    1. (a)What is a reactivity series of ​elements ? How is it developed ? Arrange the following elements as they are arranged in the reactivity series : Aluminum, Calcium, ​Copper, ​Lead
    2. (b)Write ​balanced chemical equation to ​show ​the ​reaction of iron (III) oxide ​(${\text{Fe}}_2{\text{O}}_3$) with aluminium.
    Show answer

    The reactivity series lists metals in order of decreasing reactivity; here $\text{Ca}>\text{Al}>\text{Pb}>\text{Cu}$; aluminium reacts with iron(III) oxide to give iron and aluminium oxide.

    (a) The reactivity series is a list of metals arranged in order of decreasing reactivity, the most reactive at the top. It is developed experimentally, by comparing how the metals react with oxygen, water and dilute acids and, above all, by displacement reactions — a metal that displaces another from its salt solution is placed above it. In the series the four elements come in the order Calcium $>$ Aluminium $>$ Lead $>$ Copper. (b) ${\text{Fe}}_2{\text{O}}_3(s)+2\text{Al}(s)\to 2\text{Fe}(l)+{\text{Al}}_2{\text{O}}_3(s)+\text{heat}$

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