Class 10 Science · Chapter 3

Metals and Non-metals

225 Class 10 Science questions on Metals and Non-metals from the NCERT textbook, NCERT Exemplar and CBSE board papers 2024–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 5 of 12

1. Q81 Exemplar · Short Answer Questions
   A ​non-metal A ​is an important constituent of our food and forms two oxides B and C. Oxide B is toxic ​whereas C ​causes global warming

   1. (a)Identify ​A, B and C
   2. (b)To which Group of Periodic ​Table ​does A belong?
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   A is carbon, B is toxic carbon monoxide, C is carbon dioxide (global warming); carbon is in Group 14.

   (a) A is carbon ($\text{C}$), B is carbon monoxide ($\text{CO}$), which is toxic, and C is carbon dioxide (${\text{CO}}_2$), which causes global warming. (b) Carbon belongs to Group 14 of the periodic table (the carbon family, also written as Group IVA).

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2. Q82 Exemplar · Short Answer Questions
   Give two examples each of the ​metals that are ​good conductors ​and poor ​conductors of heat respectively.
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   Good conductors of heat: silver and copper; poor conductors: lead and mercury.

   Good conductors of heat: silver ($\text{Ag}$) and copper ($\text{Cu}$). Poor conductors of heat: lead ($\text{Pb}$) and mercury ($\text{Hg}$). All four are metals, and poor here means poor in comparison with other metals.

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3. Q83 Exemplar · Short Answer Questions
   Name one metal and one non-metal that ​exist in liquid state ​at room temperature. Also ​name ​two metals ​having melting point ​less than $310$ K ($37^{\circ }$C)
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   Mercury is the liquid metal and bromine the liquid non-metal; gallium and caesium melt below $310$ K.

   The metal that is liquid at room temperature is mercury ($\text{Hg}$) and the non-metal that is liquid at room temperature is bromine (${\text{Br}}_2$). The two metals whose melting points are below $310$ K are gallium ($\text{Ga}$) and caesium ($\text{Cs}$); a small piece of either will melt on the palm of the hand.

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4. Q84 Exemplar · Short Answer Questions
   An element A reacts with water to form a compound B which is ​used in white washing. The compound B ​on heating forms ​an ​oxide C which on treatment with water ​gives back B. ​Identify A, ​B and C and give the reactions involved.
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   A is calcium, B is slaked lime ${\text{Ca(OH)}}_2$ and C is quick lime $\text{CaO}$; C with water gives B back.

   A is calcium ($\text{Ca}$), B is calcium hydroxide or slaked lime (${\text{Ca(OH)}}_2$) and C is calcium oxide or quick lime ($\text{CaO}$). The reactions are $\text{Ca}+2{\text{H}}_2\text{O}⟶{\text{Ca(OH)}}_2+{\text{H}}_2$; ${\text{Ca(OH)}}_2⟶\text{CaO}+{\text{H}}_2\text{O}$ on heating; and $\text{CaO}+{\text{H}}_2\text{O}⟶{\text{Ca(OH)}}_2$.

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5. Q85 Exemplar · Short Answer Questions
   An ​alkali metal A gives a compound B (molecular mass $=40$) on ​reacting with ​water. The compound B gives a soluble compound C on ​treatment with aluminium oxide. Identify A, B ​and C and ​give the ​reaction involved.
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   A is sodium, B is sodium hydroxide ($\text{NaOH}$, mass $40$) and C is sodium aluminate (${\text{NaAlO}}_2$).

   A is sodium ($\text{Na}$), B is sodium hydroxide ($\text{NaOH}$, molecular mass $40$) and C is sodium aluminate (${\text{NaAlO}}_2$). The reactions are $2\text{Na}+2{\text{H}}_2\text{O}⟶2\text{NaOH}+{\text{H}}_2$ and ${\text{Al}}_2{\text{O}}_3+2\text{NaOH}⟶2{\text{NaAlO}}_2+{\text{H}}_2\text{O}$.

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6. Q86 Exemplar · Short Answer Questions
   Give the ​reaction involved ​during extraction ​of zinc from its ore ​by

   1. (a)roasting of zinc ore
   2. (b)calcination ​of zinc ore
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   Roasting zinc blende gives $\text{ZnO}$ and ${\text{SO}}_2$; calcining calamine gives $\text{ZnO}$ and ${\text{CO}}_2$.

   (a) Roasting is carried out on zinc blende, the sulphide ore: $2\text{ZnS}(s)+3{\text{O}}_2(g)⟶2\text{ZnO}(s)+2{\text{SO}}_2(g)$ on strong heating in excess air. (b) Calcination is carried out on calamine, the carbonate ore: ${\text{ZnCO}}_3(s)⟶\text{ZnO}(s)+{\text{CO}}_2(g)$ on strong heating in limited air. Both give zinc oxide, which is then reduced with carbon to zinc.

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7. Q87 Exemplar · Short Answer Questions
   A ​metal M does not liberate hydrogen from acids but reacts with oxygen to ​give ​a black colour product. Identify ​M and black coloured product and ​also explain the reaction of ​M with oxygen.
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   M is copper, and heating it in air forms black copper(II) oxide: $2\text{Cu}+{\text{O}}_2\to 2\text{CuO}$.

   M is copper ($\text{Cu}$) and the black product is copper(II) oxide ($\text{CuO}$). Copper lies below hydrogen in the reactivity series, so it cannot displace hydrogen from an acid; but when it is heated in air, oxygen combines with its surface and the shining red-brown metal becomes coated with black copper(II) oxide: $2\text{Cu}(s)+{\text{O}}_2(g)⟶2\text{CuO}(s)$.

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8. Q88 Exemplar · Short Answer Questions
   An ​element forms an ​oxide ${\text{A}}_2{\text{O}}_3$ ​which ​is acidic ​in nature. Identify ​A ​as a metal or non-metal.
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   A is a non-metal, because non-metals form acidic oxides while metals form basic oxides.

   A is a non-metal. Metals form basic oxides while non-metals form acidic oxides, and the oxide ${\text{A}}_2{\text{O}}_3$ is stated to be acidic. Examples with this formula are ${\text{B}}_2{\text{O}}_3$, ${\text{N}}_2{\text{O}}_3$ and ${\text{P}}_2{\text{O}}_3$, all oxides of non-metals.

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9. Q89 Exemplar · Short Answer Questions
   A ​solution of ${\text{CuSO}}_4$ was kept in an ​iron pot. ​After few days ​the iron pot ​was found to have a number of holes in it. Explain ​the reason in ​terms of reactivity. Write the equation ​of the reaction involved.
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   Iron is more reactive than copper, so it displaces copper from ${\text{CuSO}}_4$ and dissolves, leaving holes in the pot.

   Iron is more reactive than copper, so it displaces copper from copper sulphate solution. The iron of the pot goes into solution as soluble iron(II) sulphate while copper is deposited as the free metal, and the metal lost from the wall of the pot leaves holes in it. The reaction is $\text{Fe}(s)+{\text{CuSO}}_4(aq)⟶{\text{FeSO}}_4(aq)+\text{Cu}(s)$, and the blue solution slowly turns light green.

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10. Q90 Exemplar · Long Answer Questions
    A non-metal A which is ​the largest constituent ​of air, when heated with ${\text{H}}_2$ in $1:3$ ​ratio in the presence of catalyst (Fe) gives a gas B. On heating with ${\text{O}}_2$ 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 oxidising agent.

    1. (a)Identify A, B, C and D
    2. (b)​To which group of periodic table does this non-metal belong?
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    A is nitrogen, B ammonia, C nitric oxide and D nitric acid; nitrogen belongs to Group 15.

    (a) A is nitrogen (${\text{N}}_2$), B is ammonia (${\text{NH}}_3$), C is nitric oxide ($\text{NO}$) and D is nitric acid (${\text{HNO}}_3$). The reactions are ${\text{N}}_2+3{\text{H}}_2⟶2{\text{NH}}_3$ over an iron catalyst, ${\text{N}}_2+{\text{O}}_2⟶2\text{NO}$ at a very high temperature (or $4{\text{NH}}_3+5{\text{O}}_2⟶4\text{NO}+6{\text{H}}_2\text{O}$ from B), then $2\text{NO}+{\text{O}}_2⟶2{\text{NO}}_2$ and $4{\text{NO}}_2+{\text{O}}_2+2{\text{H}}_2\text{O}⟶4{\text{HNO}}_3$, overall $4\text{NO}+3{\text{O}}_2+2{\text{H}}_2\text{O}⟶4{\text{HNO}}_3$. Naming C as nitrogen dioxide (${\text{NO}}_2$), the oxide that actually dissolves, with the same chain is also accepted. (b) Nitrogen belongs to Group 15 of the periodic table (the nitrogen family, also written as Group VA).

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11. Q91 Exemplar · Long Answer Questions
    Give ​the steps involved in ​the extraction of ​metals ​of low and medium reactivity from ​their ​respective ​sulphide ores.
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    Concentrate the ore, roast it to the oxide, reduce the oxide (heat alone for low, carbon for medium reactivity), then refine.

    For both classes the first steps are the same: the ore is crushed and concentrated, usually by froth flotation, and then roasted in excess air so that the sulphide becomes the oxide, for example $2\text{ZnS}+3{\text{O}}_2⟶2\text{ZnO}+2{\text{SO}}_2$. The routes then part at the reduction. For a metal of **low** reactivity such as mercury or copper, heat alone frees the metal: $2\text{HgO}⟶2\text{Hg}+{\text{O}}_2$, and for copper the unroasted sulphide reduces the oxide itself, $2{\text{Cu}}_2\text{O}+{\text{Cu}}_2\text{S}⟶6\text{Cu}+{\text{SO}}_2$. For a metal of **medium** reactivity such as zinc, iron or lead, the oxide is reduced with carbon: $\text{ZnO}+\text{C}⟶\text{Zn}+\text{CO}$. Finally the crude metal from either route is purified, usually by electrolytic refining.

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12. Q92 Exemplar · Long Answer Questions
    Explain the ​following

    1. (a)Reactivity of Al decreases if it is dipped ​in ${\text{HNO}}_3$
    2. (b)Carbon cannot reduce the oxides of Na or Mg
    3. (c)NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in ​aqueous solution ​as well as in molten state
    4. (d)Iron articles are ​galvanised.
    5. (e)Metals like ​Na, K, Ca ​and Mg are never found in their free state in ​nature.
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    Aluminium forms a protective oxide film, carbon cannot reduce reactive metals, free ions carry current, zinc protects iron, and reactive metals occur combined.

    (a) Nitric acid oxidises the surface of the aluminium and forms a thin, hard, impervious film of aluminium oxide on it. The film seals the metal off, so no reagent can reach it and the metal is rendered passive. (b) Sodium and magnesium lie above carbon in the reactivity series and hold oxygen more strongly than carbon does, so carbon cannot take it from their oxides; these metals are obtained instead by electrolytic reduction of their molten chlorides or oxides. (c) Sodium chloride is ionic in every state, but in the solid the ions are locked in fixed positions in the crystal lattice and cannot move, so no current flows. On melting or dissolving, the electrostatic forces are overcome, the ions become free to move and the substance conducts. (d) Galvanising coats iron with a thin layer of zinc. The zinc excludes air and moisture, and being more reactive than iron it corrodes in preference to it, so the iron is protected even where the coating is scratched. (e) Sodium, potassium, calcium and magnesium are very reactive and combine at once with the oxygen, moisture and carbon dioxide of the air, so in nature they occur only in the combined state as their compounds.

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13. Q93 Exemplar · Long Answer Questions
    (i) Given below are the steps for extraction of copper from ​its ore. Write ​the reaction involved.

    1. (a)Roasting of copper (I) sulphide
    2. (b)Reduction ​of copper (I) oxide with copper ​(I) sulphide.
    3. (c)Electrolytic refining (ii) Draw a neat and ​well labelled diagram for electrolytic refining of copper
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    Roasting forms ${\text{Cu}}_2\text{O}$, self-reduction gives copper, and electrolytic refining deposits copper at the cathode; the refining cell is drawn and labelled.

    (i) (a) Roasting: $2{\text{Cu}}_2\text{S}(s)+3{\text{O}}_2(g)⟶2{\text{Cu}}_2\text{O}(s)+2{\text{SO}}_2(g)$ on strong heating in air. (b) Reduction of copper(I) oxide by copper(I) sulphide, a self-reduction: $2{\text{Cu}}_2\text{O}(s)+{\text{Cu}}_2\text{S}(s)⟶6\text{Cu}(s)+{\text{SO}}_2(g)$ on heating. (c) Electrolytic refining, in acidified copper sulphate solution: at the anode $\text{Cu}(s)⟶{\text{Cu}}^{2+}(aq)+2e^{-}$, and at the cathode ${\text{Cu}}^{2+}(aq)+2e^{-}⟶\text{Cu}(s)$. (ii) The labelled diagram is given above: a vessel of acidified copper sulphate solution, the thick block of impure copper as the anode joined to the positive terminal, the thin strip of pure copper as the cathode joined to the negative terminal, copper ions moving from anode to cathode, and the anode mud collecting below the anode.

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14. Q94 Exemplar · Long Answer Questions
    Of the three metals X, Y and ​Z. X ​reacts with cold water, Y with hot water ​and Z with steam only. ​Identify X, Y and ​Z ​and ​also arrange them in order of increasing reactivity.
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    X is sodium, Y is magnesium and Z is iron; reactivity increases in the order iron, magnesium, sodium.

    X is sodium ($\text{Na}$), Y is magnesium ($\text{Mg}$) and Z is iron ($\text{Fe}$). The order of increasing reactivity is $\text{Z}<\text{Y}<\text{X}$, that is iron $<$ magnesium $<$ sodium. The reactions are $2\text{Na}+2{\text{H}}_2\text{O}⟶2\text{NaOH}+{\text{H}}_2$ with cold water, $\text{Mg}+2{\text{H}}_2\text{O}⟶{\text{Mg(OH)}}_2+{\text{H}}_2$ with hot water, and $3\text{Fe}+4{\text{H}}_2\text{O}⟶{\text{Fe}}_3{\text{O}}_4+4{\text{H}}_2$ with steam. Other choices fit the same pattern and are equally acceptable: X could be potassium or calcium, and Z could be zinc or aluminium; the order of increasing reactivity is unchanged.

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15. Q95 Exemplar · Long Answer Questions
    An element A burns with golden flame in air. It reacts with ​another element B, atomic number 17 to give ​a product ​C. An aqueous solution of product C on electrolysis gives ​a compound D and liberates hydrogen. ​Identify A, B, C and ​D. ​Also write down the ​equations for the reactions involved.
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    A is sodium, B chlorine, C sodium chloride and D sodium hydroxide, formed by electrolysis of brine.

    A is sodium ($\text{Na}$), B is chlorine ($\text{Cl}$, atomic number $17$), C is sodium chloride ($\text{NaCl}$) and D is sodium hydroxide ($\text{NaOH}$). The reactions are $4\text{Na}+{\text{O}}_2⟶2{\text{Na}}_2\text{O}$ when sodium burns in air with its golden flame, $2\text{Na}+{\text{Cl}}_2⟶2\text{NaCl}$, and $2\text{NaCl}(aq)+2{\text{H}}_2\text{O}(l)⟶2\text{NaOH}(aq)+{\text{Cl}}_2(g)+{\text{H}}_2(g)$ on electrolysis, which is the chlor-alkali process.

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16. Q96 Exemplar · Long Answer Questions
    Two ores ​A and B were taken. On heating ore ​A gives ${\text{CO}}_2$ whereas, ​ore B gives ${\text{SO}}_2$. ​What steps will you take to convert ​them ​into ​metals?
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    Crush and concentrate both ores; calcine the carbonate ore A and roast the sulphide ore B to oxides, reduce with carbon, then refine.

    Ore A gives carbon dioxide, so it is a carbonate ore; ore B gives sulphur dioxide, so it is a sulphide ore. Both are first crushed and concentrated. Ore A is then **calcined**, heated strongly in the absence or limited supply of air, ${\text{MCO}}_3⟶\text{MO}+{\text{CO}}_2$; ore B is **roasted**, heated strongly in excess air, $2\text{MS}+3{\text{O}}_2⟶2\text{MO}+2{\text{SO}}_2$. Both now give the metal oxide, which is reduced with carbon, $\text{MO}+\text{C}⟶\text{M}+\text{CO}$. Finally each crude metal is purified, usually by electrolytic refining. If the metal were a highly reactive one, the oxide could not be reduced with carbon and the metal would be obtained by electrolysis of its molten salt instead.

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17. Q97 CBSE 2026
    Although ​most of the metals ​form basic oxides, ​which ​of ​the following metals forms ​an amphoteric ​oxide ?

    1. (a)Na
    2. (b)Ca
    3. (c)Al
    4. (d)Cu
    Show answer

    (c) Al

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18. Q98 CBSE 2026
    Which of ​the following ​metals ​is ​a ​poor conductor of heat ?

    1. (a)Na
    2. (b)Pb
    3. (c)Cu
    4. (d)Al
    Show answer

    (b) Pb

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19. Q99 CBSE 2026
    Which of ​the following metals ​has ​a ​very low ​melting point ?

    1. (a)Copper
    2. (b)Sodium
    3. (c)Aluminium
    4. (d)Caesium
    Show answer

    (d) Caesium

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20. Q100 CBSE 2026
    Which ​of the ​following ​is ​an ​amphoteric oxide ?

    1. (a)${\text{Na}}_2\text{O}$
    2. (b)${\text{K}}_2\text{O}$
    3. (c)${\text{CO}}_2$
    4. (d)${\text{Al}}_2{\text{O}}_3$
    Show answer

    (d) ${\text{Al}}_2{\text{O}}_3$

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