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CBSE Solutions for Class 10 English

GSEB std 10 science solution for Gujarati check Subject Chapters Wise::

What is the common feature within the electronic configuration of metal atoms ?

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જવાબ : The metal atoms generally have one, two or maximum of three valence electrons which they will easily lose to make cations or positive ions.


Name a metal aside from aluminium that's covered with a layer of oxide film.

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જવાબ : Iron (Fe) is additionally covered with a layer of its oxide (Fe2O3) when kept exposed to air for an extended time.


Why do silver articles become black after a while ?

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જવાબ : Traces of hydrogen sulphide (H2S) gas are present in air/atmosphere. It slowly reacts with silver to make silver sulphide which is black. As a result, silver ornaments lose their shine after sometime.


A shining metal ‘X’ on heating in air becomes black in colour. Name the black coloured compound formed and identify ‘X’.

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જવાબ : The black coloured compound is copper (II) oxide or cupric oxide. The metal ‘X’ is copper.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 1


Alloys are utilized in electrically heating devices instead of pure metals. Give one reason.
(CBSE All India 2009)

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જવાબ : Alloys are generally the mixture of two or more metals. Since metals are good conductors of electricity, a mixture of metals i.e., alloy is predicted to be a far better conductor of electricity than the pure metal,


The electronic configuration of an elements ‘E’ (Z = 16) is 2, 8, 6. Will it lose six electrons or gain two electrons ?

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જવાબ : It will gain two electrons.


Write the names of two neutral oxides. (CBSE 2010)

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જવાબ : Two neutral oxides are : carbon monoxide gas (CO) and laughing gas (N2O).


Name the formula of blende and galena.

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જવાબ : Zinc blende is zinc sulphide (ZnS) while galena is lead sulphide (PbS).


Write one example each of :
a metal having low freezing point and a metal having high freezing point .
a metal which may be a poor conductor of electricity and a non-metal which may be a good conductor of electricity.

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જવાબ : Gallium (Ga) may be a metal with very low freezing point (302 K). Diamond (carbon) may be a non-metal with very high freezing point . (4000 K)
Metal lead (Pb) may be a poor conductor of electricity whereas graphite (carbon) may be a good conductor of electricity.


Which acts as anode within the electro-refining of metals ?

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જવાબ : A plate of impure metal acts as anode within the electro-refining of metals.


What is the name of the bond formed when a metal atom combines with the atom of a non-metal ? (CBSE 2010)

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જવાબ : Bond formed is ionic or electrovalent.


How will you account for the high melting points of salts ?

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જવાબ : The high melting points of salts are thanks to their closely packed structures and also thanks to stronger forces of attraction within the oppositely charged ions.


Name two metals which exist within the native or free state.

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જવાબ : Metals gold (Au) and platinum (Pt) exist within the free or native state.


What reaction takes place when manganese dioxide is heated with aluminium powder ?

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જવાબ : 3MnO2(s) + 4Al(s) ————> 3Mn(l) + 2Al2O3(s)


Can rusting of iron nail occur in water ?

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જવાબ : No, because water has no dissolved oxygen in it.


Which metal is employed in amalgams ?

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જવાબ : Mercury (Hg) is employed in amalgams that also are alloys in nature.

 


Which metal is that the best conductor of electricity ? (CBSE 2010)

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જવાબ : Silver (Ag) is that the best conductor of electricity.


Why are metals conducting in nature ?

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જવાબ : The conductivity of metals is thanks to the movement of electrons. These are mobile even within the solid state.


Why do metals generally appear to be dull ?

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જવાબ : When metals are kept exposed to air for sometime, oxygen present in air slowly combines with the metal to make metal oxide. it's deposited as a layer on the surface of metals. they seem to be dull.


Name two non-metals which exist within the solid state and two non-metals which exist within the gaseous state.

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જવાબ : Solid State : Sulphur, phosphorus;
Gaseous state : Nitrogen, oxygen.


Name the metal whose foils are used for the packing of food materials.
 

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જવાબ : Aluminium foils are used for the aim .


Name the non-metal which may conduct electricity.

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જવાબ : Graphite, an allotropie sort of carbon conducts electricity.


Write the chemical formulae of the most ores of iron and aluminium.

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જવાબ : The main ore of iron is haematite (Fe2CO3) while that of aluminium is bauxite (Al2O3.2H2O).


Does nickel silver contain silver in it ?

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જવાબ : German silver is an alloy of copper, zinc and nickel. It doesn't contain any silver in it.


How do alloys brass and bronze differ in composition ? (CBSE 2010)

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જવાબ : Constituents of brass are copper and zinc while those of bronze are copper and tin.


Out of zinc and iron, which evolves hydrogen more readily on reacting with dilute HCl ?

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જવાબ : Zinc evolves hydrogen more readily than iron on reacting with dilute HCl because it's placed above iron within the reactivity series.


Name the method used for the enrichment of sulphide ore.

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જવાબ : The process is named Froth Floatation process.


What is the formula of rust ?
 

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જવાબ : Rust is hydrated oxide and its formula is Fe2O3.xH2O.


What is the difference between calcination and roasting ?

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જવાબ : Calcination is carried within the absence of air while roasting is completed in more than air.


Name the metal which is most abundant in earth’s crust.
 

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જવાબ : Aluminium (Al) is the most abundant metal in the earth’s crust and is present to the extent of 8-1 per cent by mass.


The rocky material found along with ores is known as …………….

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જવાબ : Answer: gangue


Non-metals are ……………. in character.

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જવાબ : Answer: electronegative


The chlorides of non-metals are …………….

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જવાબ : covalent


A sulphide ore is concentrated by …………….

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જવાબ : Answer: froth flotation process


Oxides of non-metals when dissolved in water generally give ……………. solutions.

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જવાબ : acidic


Removal of impurities from a metal by chemical method is called …………….

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જવાબ : leaching


……………. displaces copper from a solution of copper (II) sulphate.

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જવાબ : Zinc


Metal have ……………. melting and boiling points.

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જવાબ : high


The process in which the concentrated ore is heated below its melting point in the absence or limited supply of air is called …………….

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જવાબ : Calcination


Metal oxides ……… and ……… dissolve in water to form alkalis.

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જવાબ : Sodium Oxide and Potassium oxide


Metals which are so soft that they can be cut with a knife are ………, ………

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જવાબ : Sodium, Potassium


……… is an allotroph of carbon and is the hardest natural substance.

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જવાબ :  Diamond


The extraction of metals from their ores and then refining them for use is known as ……… .

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જવાબ : metallurgy


Metals above hydrogen in the activity series can displace ……… from dilute acids.

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જવાબ : Hydrogen


A metal which burns in air with a dazzling white flame is ……… .

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જવાબ : Magnesium


A non-metal which is lustrous is ……… .

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જવાબ : Iodine


Metals can form positive ions by ……… .

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જવાબ : losing electrons


A non-metal which is a good conductor of electricity is ……… .

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જવાબ : Graphite


Two metals which melt when kept on the palm are ………, ……… .

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જવાબ : Gallium, Caesium


Two metals which melt when kept on the palm are ………, ……… .

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જવાબ : Gallium, Caesium


Elements can be classified as ……… and ……. .

 
 
 
 
 
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જવાબ : metals, non-metals


How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle ? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium.

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જવાબ : Metals high up in the series are obtained by electrolytic reduction because these metals are strong reducing agents and therefore, cannot be obtained by chemical reduction.
Metals in middle of series are less reactive and can be obtained by chemical reduction. The same process can not be used for both of them as highly reactive metals can not be obtained by chemical reduction.
Extraction of sodium is done by electrolysis of molten sodium chloride.
metals-non-metals-chapter-wise-important-questions-class-10-science-25


(a) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why?
(b) How is sodium obtained from molten sodium chloride? Give equation of the reactions.
(c) How is copper obtained from its sulphide ore? Give equations of the reactions.

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જવાબ : (a) It is because ‘Mg’ is stronger reducing agent than carbon.
(b) Sodium is obtained from molten NaCl by electrolysis.

metals-non-metals-chapter-wise-important-questions-class-10-science-24
Blister Copper is purified by electrolytic refining.


(a) In the formation of compound between two atoms A and B, A loses two electrons and B gains one electron.
(i) What is the nature of bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of MgCl2 molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of NaCl high?

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જવાબ : metals-non-metals-chapter-wise-important-questions-class-10-science-23


(a) Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equations. How is zinc extracted from its ore?
(b) Name two metals that can be used to reduce metal oxides to metals.

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જવાબ : (a) Roasting: It is a process in which sulphide ore is heated in the presence of oxygen to convert into oxide.
metals-non-metals-chapter-wise-important-questions-class-10-science-20
Cali ination: It is a process in which carbonate ore is heated in the absence of air to form oxide.
metals-non-metals-chapter-wise-important-questions-class-10-science-21
By reduction process, Zn can be extracted from its ore.
metals-non-metals-chapter-wise-important-questions-class-10-science-22
(b) Aluminium, Magnesium.


(a) Write the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air.
(b) Explain what is galvanisation. What purpose is served by it?
(c) Define an alloy. How are alloys prepared? How do the properties of iron change when:
(i) small quantity of carbon,
(ii) nickel and chromium are mixed with it.

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જવાબ : (a) Ag2S (silver sulphide) is formed on silver, basic copper carbonate CuCO3. CU(OH)2 is formed on copper.
(b) The process of coating zinc over iron is called galvanisation. It is used to prevent rusting of iron.
(c) Alloy is a homogeneous mixture of two or more metals. One of them can be non-metal. Alloys are prepared by melting two or more metals together.
(?) Iron does not rust on adding small,quantity of carbon.
(ii) When we form alloy of iron with nickel and chromium, we get stainless steel which is malleable and does not get rusted.


With reference to electrorefining of impure copper, answer the following :
(a) Draw a neat and labelled diagram required for the purpose of electrorefining.
(b) What is the electrolyte used ?
(c) Name the cathode and anode used.
(d) What happens at cathode and anode 

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જવાબ : (a) For the labelled diagram,
NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and Non-metals 27
(b) An aqueous solution of copper sulphate containing a small amount of sulphuric acid is used as the
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 25


(a) Most metals do not react with bases but zinc metal does. Suggest a reason. Write an equation for the reaction between Zn and NaOH.
(b) When a metal X is treated with cold water, it gives a base Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z.

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જવાબ : (a) We know that zinc oxide (ZnO) is of amphoteric nature. The metal zinc also behaves similarly. It reacts with both acids and alkalies. For example,
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 23
(b) Molecular mass of base Y = 40 Atomic mass of X = 40 – (16 + 1) = 23
The metal X is sodium (Na). The salt Y is NaOH and liberated gas Z is, hydrogen.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 24


(a) Which method will you use to reduce the following ? Explain by giving a suitable example.
(i) Oxides of less reactive metals
(ii) Oxides of moderately reactive metals
(iii) Oxides of highly reactive metals.
(b) The reaction between metal ‘X’ and Fe2O3 is highly exothermic and is used to join railway tracks.
(i) Identify metal ‘X’ and name the reaction.
(ii) Write the chemical equation of its reaction with Fe2O

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જવાબ : (a) (i) Oxides of less reactive metals can be reduced either by auto-reduction or upon heating. For example,
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 20
(ii) Oxides of moderately reactive metals can be reduced with coke. This is known as smelting. For example,
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 21
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 22


(a) Write the balanced chemical equations for the extraction of copper metal from its ore. What is the reducing agent used ?
(b) Which reducing agent can be used in the extraction of metals placed at the top of the reactivity series ? Give the name of the process also.
(c) What is the chemical substance formed as green coating when copper reacts with atmospheric gases in moist conditions ?

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જવાબ : (a) Copper is isolated from its sulphide ore known as copper glance (Cu2S) by heating with excess of air or oxygen.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 18
Cuprous oxide (Cu2O) acts as reducing agent and this process is known as auto-reduction.
(b) These metals (K, Na, Ca, Mg etc.) can be isolated by carrying out the process of electrolysis (electrolytic reduction) from their molten salts.
(c) The green coating is of basic copper carbonate. It is formed as follows :

Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 19


(a) Give an example of a metal which

  1. is a liquid at room temperature.
  2. is kept immersed in kerosene for storing.
  3. is both malleable and ductile.
  4. is the best conductor of heat.
(b) Name the process of obtaining a pure metal from an impure metal through electrolysis. Suppose you have to refine copper using this process, then explain with the help of a labelled diagram the process of purification, mentioning in brief the materials used as (i) anode (ii) cathode and (iii) electrolyte.

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જવાબ : (a)

  1. Mercury (Hg) is liquid at room temperature :
  2. Sodium (Na) is kept immersed in kerosene for storing.
  3. Aluminium (Al) is malleable and ductile
  4. Silver (Ag) is the best conductor of heat.
(b) The process is known as electro-refining. For the electro-refining of copper,
The conversion of a crude metal into pure metal is known as metal refining.
The refining can be done in a number of ways but the most common among these is the electro-refining and is discussed.
This method is commonly used for the purification of the metals like Cu, Ag, Zn, Ni etc. The impure metal is converted into a block which is made anode in an electrolytic cell in which a plate of pure metal acts as the cathode as shown in the Figure 3.16.
NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and Non-metals 27The electrolyte is the solution of the soluble salt of the same metal, preferably a double salt. On passing electric current, metal ions from the electrolyte are reduced to the metal which is deposited on the cathode. An equivalent amount of the pure metal from the anode gets oxidised and the metal ions (or cations) go into the solution. This keeps on till the whole of the metal from the anode dissolves and deposits on cathode, leaving behind impurities in the form of a mud called anode mud.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 28
For example, in the electro-refining of crude copper, impure metal is made anode and a plate of pure copper acts as the cathode. These are connected through a battery in the external circuit as shown in the figure. The electrolyte is aqueous solution of copper sulphate containing a small amount of sulphuric acid. On passing current, the following changes occur.


(a) Distinguish between ‘roasting’ and ‘calcination’. Which of the two is used for sulphide ores and why ?
(b) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines.
(c) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.

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જવાબ : (a) For distinction between calcination and roasting,

Calcination

Roasting

(i) Calcination is carried in absence of air or oxygen.

Roasting is carried in the presence of excess of air.

(ii) As a result of calcination, the carbonate ore is converted to the oxide form.

As a result of roasting, the sulphide ore is converted to the oxide form.

ZnCO3(s) —— > ZnO(s) + CO2(g)

2ZnS(s)+3O2(g)—– > 2ZnO(s)+2SO2(g)

For the sulphide ores, the process of roasting is commonly used. It is carried by heating the ore helow its melting point with excess of air. As a result, the sulphide ore is converted to its oxide form. For example,
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 16
(b) Cracked railway lines can be joined or welded with the help of thermit welding. Thermit is a mixture of ferric oxide and aluminium powder. The chemical equation involved is :
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 17
(c) In the electrolytic refining of copper ;
Anode : A rod of impure copper.
Cathode : A rod of pure copper.
Electrolyte : An aqueous solution of copper sulphate containing a small amount of sulphuric acid.

(a) Distinguish between ‘roasting’ and ‘calcination’. Which of the two is used for sulphide ores and why ?
(b) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines.
(c) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.
Answer:
(a) For distinction between calcination and roasting,

Calcination

Roasting

(i) Calcination is carried in absence of air or oxygen.

Roasting is carried in the presence of excess of air.

(ii) As a result of calcination, the carbonate ore is converted to the oxide form.

As a result of roasting, the sulphide ore is converted to the oxide form.

ZnCO3(s) —— > ZnO(s) + CO2(g)

2ZnS(s)+3O2(g)—– > 2ZnO(s)+2SO2(g)

For the sulphide ores, the process of roasting is commonly used. It is carried by heating the ore helow its melting point with excess of air. As a result, the sulphide ore is converted to its oxide form. For example,
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 16
(b) Cracked railway lines can be joined or welded with the help of thermit welding. Thermit is a mixture of ferric oxide and aluminium powder. The chemical equation involved is :
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 17
(c) In the electrolytic refining of copper ;
Anode : A rod of impure copper.
Cathode : A rod of pure copper.
Electrolyte : An aqueous solution of copper sulphate containing a small amount of sulphuric acid.


Give reasons for the following :

  1. Zinc can displace copper from copper sulphate solution.
  2. Silver articles become black after sometime when exposed to air.
  3. A metal sulphide is converted to its oxide to extract the metal from sulphide ore.
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જવાબ :

  1. Zinc is placed above copper in the activity series. Therefore, it can easily displace copper from copper sulphate solution.
    Zn(s) + CuSO4(aq) ————> ZnSO4(aq) + Cu(s)
  2. Air contains traces of hydrogen sulphide (H2S) gas. Silver has a tendency to combine with H2S to form silver sulphide (Ag2S) which is black in colour. On account of this, silver articles become black after some time when kept exposed to air.
  3. A metal sulphide is normally converted into oxide by heating with excess of air or oxygen. This process is called roasting. Actually, the oxide of metal which is formed cap be easily reduced to the metallic form by reduction with carbon or some electropositive element. For example,
    Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 15


(a) Define corrosion; what is the nature given to corrosion of iron ?
(b) Name the colour of coating formed on silver and copper when exposed to air.
(c) List two damages caused by corrosion and suggest, how these can be prevented.

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જવાબ : (a) For definition of corrosion: The process of slow eating up of a metal by the gases and water vapours present in air due to formation of certain chemical compounds. Corrosion of iron is known as rusting.
(b) Coating deposited on the surface of silver metal is of silver sulphide (Ag2S). It is black in colour. The coating deposited on copper surface is of basic copper carbonate Cu(OH)2CuCO3. It is green in colour.

Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 27
(c) Corrosion of metals particularly the rusting of iron is very harmful. The structures made from iron are generally placed in the open. These are slowly corroded or rusted. This reduces their strength gradually. They become prone to accidents and are therefore, quite dangerous. A lot of care and money is involved in their maintenance. However, corrosion of aluminium has advantage. The metal placed high in the activity series is quite reactive. It combines with the oxygen present in air to form aluminium oxide (Al2O3).


With a suitable activity show that sulphur burns in air to form a compound which is acidic in nature.

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જવાબ :

  1. Take a small amount of sulphur powder on a spatula.
  2. Now burn this powder by placing a tube in a inverted position over the spatula as shown in the figure.
  3. The fumes produced as a result of burning of sulphur will get collected in the tube.
  4. Place the tube in vertical position and immediately add some water to it.
  5. Shake the tube so that the fumes may completely dissolve.
  6. Add a few drops of blue litmus to a portion of the solution. It will acquire red colour which shows that it is of acidic nature.
  7. To another portion, add a few drops of red litmus solution. No colour change will be noticed. This shows that the solution is not acidic.
    Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 13
Explanation : Sulphur burns in air to form sulphur dioxide which escapes from the tube as fumes with pungent and suffocating smell. The gas produced readily dissolves in water to form sulphurous acid (H2SO3). The solution is therefore, acidic. It will change the colour of blue litmus to red.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 14


How will your demonstrate that the ionic compounds do not conduct electricity in the solid state and can do so in solution.

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જવાબ :

  1. In a glass beaker, take small amount of solid sodium chloride.
  2. Dip two graphite rods (electrodes) in the solution.
  3. Connect these rods to a battery through a bulb and a switch.
  4. Switch on the battery. The bulb will not glow. This show that no current has passed through the solid sodium chloride.
  5. Now, add some water to the salt so that it may dissolve.
  6. Repeat the operation. The bulb will immediately glow showing that current has passed through the salt solution.
    Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 12
Explanation: Sodium chloride (NaCl) is a crystalline solid and the current is carried by the mobility (movement) of ions. Since the ions do not move in the solid state, the salt is not conducting. In aqueous solution, both Na+ and Cl- ions can move and the salt will be conducting in the solution. That is why the bulb glows.


(a) Which of the following metals would give hydrogen when added to dilute hydrochloricacid?

  1. iron
  2. copper
  3. magnesium ?
(b)Explain why do surfaces of some metals acquire a dull appearance when exposed to air for a long lime.

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જવાબ : (a) Both iron (Fe) and magnesium (Mg) will evolve hydrogen on reacting with dilute hydrochloric acid. These are active metals and are placed above hydrogen in the activity series. As copper is placed below hydrogen in the series, it will not evolve hydrogen.
(b) Surfaces of some metals acquire a dull appearance when exposed to air for a long time and they lose their lustre. This is due to the formation of layer of oxides, hydroxides, carbonates etc. on the surface For example, surface of aluminium metal becomes dull white due to the formation of coating oi aluminium oxide (Al2O3). Similarly, the surface of copper acquires a greenish colour since a layer oi basic copper carbonate with the formula Cu(OH)2CuCO3 is deposited on the surface.


When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen gas is passed over the hot black substance formed, it regains its original colour. Based on this information, answer the following questions :

  1. What type of chemical reaction takes place in each of the two given steps ?
  2. Name the metal initially taken in the powder form. Write balanced chemical equations for both these reactions.
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જવાબ :

  1. The available information suggests the metal is copper. In open air, its is oxidised to form copper (II) oxide which is black in colour. The reaction is known as oxidation reaction. On passing hydrogen gas over the hot substance, the original colour of the metal is regained. It is an example of reduction reaction.
  2. The balanced chemical equations for the reactions are :
    Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 11


Metallic compound A reacts with dilute hydrochloric acid to produce effervescence and a gas B. The gas B extinguishes a burning candle and also turns lime water milky. Identify A and B. Write balanced chemical equations for the reactions involved.

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જવાબ : The available information suggests that the gas B is CO2 since it turns lime water milky. The compound A is the carbonate or bicarbonate of some metal (e.g. calcium earbonate) The equations for the reactions involved are given :
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 10


The way metals like sodium, magnesium and iron react with air and water, is an indication of their relative positions in the ‘reactivity series’. Is this statement true ? Justify your answer with examples. 

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જવાબ : Yes, the statement is true. We can have an idea about the relative positions of these metals in the reactivity series. For example,
(a) Sodium reacts violently even with cold water and with air or oxygen it readily combines.
(b) Magnesium reacts with hot water and with air or oxygen upon heating.
(c) Iron reacts with steam only and with air it reacts very slowly
This shows that the relative positions of these metals in the activity series are : sodium, magnesium,


(a) Using a simple experiment, how can you prove that magnesium is placed above zinc in the reactivity ?
(b) Why cannot copper metal liberate hydrogen on reacting with acid     . HCl ?

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જવાબ : (a) In a glass tube, take about 10 mL of aqueous solution of zinc sulphate. It is colourless. Dip a small and dry piece of magnesium ribbon in the solution. It slowly dissolves and greyish mass gets deposited at the bottom of the tube. This shows that magnesium is more reactive than zinc or it is placed above zinc in the activity series.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 9
(b) Copper lies below hydrogen in the reactivity series and cannot lose electrons to H+ ions of the acid. This means that hydrogen gas cannot be liberated.


(a) what's the activity series of metals ? Arrange the metals Zn, Mg, Al, Cu and Fe during a decreasing order of reactivity.
(b) What would you observe once you put
1. some zinc pieces into blue copper sulfate solution ?
2. some copper pieces into green ferrous sulphate solution ?
(c) Name a metal which mixes with hydrogen gas. Name the compound formed.

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જવાબ : (a) we discover that zinc occupies a way higher position within the acitivity series as compared to copper. it's expected to displace copper present within the solution of its salt (e.g. CuSO4).

Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 26
(b)

  1. Blue colour of copper sulphate solution would slowly disappear.
  2. No change would be noticed.
(c) Sodium combines with hydrogen to form sodium hydride.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 7


(a) Why is ZnO called an atmospheric oxide? Name another atmospheric oxide?
(b) Whar are alkalies? Give one exampleof alkalies?

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જવાબ : (a)
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 6
Aluminium oxide (Al2O3) is another amphoteric oxide.
(b) Water soluble hydroxides of metals are known as alkalis. For example, NaOH.


Give reasons for the subsequent :
Metals replace hydrogen from dilute acids whereas non-metals don't .

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જવાબ : Metals are electropositive in nature. Their atoms readily lose electrons to make positive ions. The electrons are accepted by H+ ions of the acid to evolve hydrogen gas. for instance ,
Zn(s) ———-> Zn2+(aq) + 2e– ;
2H+(aq) + 2e– ————> H2(g)
Non-metals are electronegative in nature. this suggests that their atoms can take up electrons and can't lose them. Therefore, they are doing not evolve hydrogen on reacting with dilute acids.


Name an ore of zinc aside from flowers of zinc . By which process can this ore be converted into flowers of zinc ?

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જવાબ : The ore of zinc aside from flowers of zinc (zincite) is zinc carbonate (calamine). it's the formula ZnCO3 Calamine is converted into flowers of zinc by calcination i.e., by heating strongly within the absence of air.

Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 5


Which method of concentration of ore is preferred within the following cases and why ?
1. The ore has higher density particles mixed with an outsized bulk of rarity impurities.
2. The ore consists of copper sulphide intermixed with clay particles.
Give an example of amalgam.

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જવાબ : 1. The concentration of ore are often done by gravity separation method.
2. The concentration of ore is completed by Froth Floatation process.
An amalgam of mercury with silver or gold called dental alloy is employed to fill cavities within the teeth.


On placing a bit of zinc metal during a solution of mercury chloride , it acquires a silvery surface but when it's placed during a solution of magnesium sulphate, no change is observed. State the rationale for the behaviour of zinc metal.

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જવાબ : Zinc lies above mercury within the activity series and may easily replace it from mercury chloride solution. Mercury formed within the reaction gets deposited on the surface of zinc to offer it a silvery look.
Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 4
But zinc is placed below magnesium in the activity series. Therefore, no chemical reaction occurs between zinc and magnesium sulphate solution.


A copper plate was dipped into an answer of AgNO3. After sometime, a black layer was deposited on the copper plate. State the rationale for it. Write the chemical equation for the reaction involved.

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જવાબ : Copper lies above silver within the activity series. this suggests that copper is more reactive than silver. Therefore, copper had replaced silver from AgNO3 solution. Silver got deposited on the copper plate and altered to black after sometime because silver and also some salts of silver are sensitive to light. They readily become blackish on standing or on exposure to air.Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 3


Why is titanium is called as a strategic metal? Mention two of its properties which make it so special.

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જવાબ : Titanium is called strategic metal because it is used for making certain war equipments. The properties which make the metal so special are :

  1. It is light in weight but at the same time stronger than the other metals.
  2. It is not affected by corrosion even if kept in the open for a very long time.


(a) An iron knife kept in blue copper sulfate solution turns the blue solution into light green. Explain.
(b) An athlete won a trophy during a race competition. After some days, he found that the medal had lost its lustre thanks to the formation of a greenish layer thereon . Name the metals present within the medal. what's the rationale for the looks of a greenish layer on its surface ?

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જવાબ : (a) Iron lies above copper within the activity series. this suggests that iron or iron knife will displace copper from copper sulfate solution. As a results of the reaction, ferrous sulphate are going to be formed and therefore the solution are going to be light green in colour.

Previous Year Question Papers for CBSE Class 10 Science Chapter 3 Metals and Non-metals 2
(b) The bronze medal is an alloy and the constituting metals are copper and tin.
The loss of lustre by the medal is due to the formation of a coating of green layer. This layer is at basic copper carbonate.


“All ores are minerals but all minerals are not ores”. Give explanation for the statement.

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જવાબ : In the earth’s crust, metals are present within the sort of minerals and there are quite one mineral for a specific metal. However, metal might not be extracted from all of them. The mineral from which a metal are often profitably and conveniently extracted is understood as ore. This clearly means all ores are minerals but all minerals aren't ores. for instance the various minerals of iron are :
Haematite : Fe2O3 ;
Limonite : Fe2O3.3H2O;
Siderite : FeCO3 ;
Iron pyrites : FeS2
Iron is extracted from haematite (Fe2CO3). Haematite mineral is that the ore of iron while other minerals aren't the ores.


There are No Content Availble For this Chapter

Direction: Match Column I with Column II.

Column I

Column II

(i) Sodium

(A) forms black oxide

(ii) Copper

(B) forms black metal sulphide

(iii) Silver

(C) occurs in free state

(iv) Gold

(D) reacts explosively with cold water

(v) Zinc

(E) used in galvanisation

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જવાબ :

(i) (D)
(ii) (A)
(iii) (B)
(iv) (C)
(v) (E)

Metal which melt if you keep them on your palm

Ore

Metal which melt if you keep them on your palm

Sodium

Substance from which metal can be extracted by metallurgy
 

Caesium

Metal which can be cut with knife

 

Corrosion

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જવાબ :

 Caesium
 Corrosion
 Ore
 Sodium

A homogeneous mixture of two or more metals
 

. Brass

An alloy of copper and zinc

Iodine

Property of metal due to which metal produce a sound on striking a hard surface

Alloy

Lustrous non-metal

Sonorous

 

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જવાબ :

Alloy

Brass

Sonorous
Iodine

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