NCERT Solution Science Class 10 Chapter 3 Metals and Nonmetals

NCERT Solution Science Class 10 Chapter 3 Metals and Nonmetals

NCERT Solution Science Class 10 Chapter 3 Metals and Nonmetals all questions and answers. Science Class 10 3rd Chapter Metals and Nonmetals exercise solution and experts answer. As one of online learning platforms, we (netex.) are excited to offer the NCERT Solution Science Class 10 Chapter 3. This solution is designed to help students who are looking to brush up on their Science concepts on Chapter 3 Metals and Nonmetals.

Page no: 40

1.) Give an example of a metal which

(i) is a liquid at room temperature.

(ii) can be easily cut with a knife.

(iii) is the best conductor of heat.

(iv) is a poor conductor of heat.

Ans 1- (i) Mercury

(ii) Lithium, sodium and potassium

(iii) Silver and Copper

(iv) Lead and mercury

2.) Explain the meanings of malleable and ductile.

Ans2- • Malleable: The metals that can beaten into thin sheets.

E.g- Gold and silver

  • Ductile: The metals that can drawn into thin wires.

E.g- Gold

Page no: 46

1.) Why is sodium kept immersed in kerosene oil?

Ans1- Sodium is kept immersed in kerosene because it is a very reactive metal & when its kept exposed to air,  it reacts with the air and catch fire.

2.) Write equations for the reactions of

(i) iron with steam

(ii) calcium and potassium with water

Ans 2- (i) 3Fe(s) + 4 H2O gives Fe3O4(s) + 4H2(g)

(ii) • 2K(s) + 2H2O(l) gives 2KOH(aq) + H2(g) + Energy

  • Ca(s) + 2H2O(l) gives Ca(OH)2 (aq) + H2(g)

3.) Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Use the Table above to answer the following questions about metals A, B, C and D.

(i) Which is the most reactive metal?

(ii) What would you observe if B is added to a solution of Copper(II) sulphate?

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Ans3- i) B is the most reactive metal as it displaces all the metal from their solutions.

ii) B will displace the copper from its copper sulphate solution. As it is the most reactive metal.

iii) Reactivity- B > A > C > D

4.) Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.

Ans4- Hydrogen gas is produce when dilute Hydrochloric acid is added to a reactive metal.

Reaction- Fe(s) + H2SO4(aq) gives FeSO4(aq) + H2(g)

5.) What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.

Ans 5- Zinc displaces the Iron from its Iron(II) Sulphate as zinc is more reactive than iron.

Reaction: Zn(s) + FeSO4(aq) gives ZnSO4(aq) + Fe(s)

Page no: 49

1.) (i) Write the electron-dot structures for sodium, oxygen and magnesium.

(ii) Show the formation of Na2O and MgO by the transfer of electrons.

(iii) What are the ions present in these compounds?

Ans 1- i)

ii)

iii) The ions present in Na2O is Na+ and O2- & the MgO contains Mg2+ and O2-.

2.) Why do ionic compounds have high melting points?

Ans 2- Ionic solids have strong force of inter- Ionic attraction. To overcome that very high amount of energy is required. Therefore, high Melting points.

Page no: 53

1.) Define the following terms. (i) Mineral (ii) Ore (iii) Gangue

Ans 1- i) The elements or compounds which occur naturally in the earth’s crust are called as minerals.

ii) Ores- Minerals consist of high percentage of metal and that can be profitably extracted from it. The minerals are called ores.

iii) Gangue- Ores mined from the earth contains large amounts of impurities such as soil, sand etc. These are called gangue.

2.) Name two metals which are found in nature in the free state.

Ans 2- Gold and silver are found in free state because they are less reactive.

3.) What chemical process is used for obtaining a metal from its oxide?

Ans 3- A metal is extracted from metal oxide by the process of Reduction by either using a reducing agent or just by heating.

E.g.: ZnO(s) + C gives Zn(s) + CO(g)

Page no: 55

1.) Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Ans 1- Table-

Metal

Zinc Magnesium Copper
Zinc oxide No reaction Displacement

No reaction

Magnesium oxide

No reaction No reaction No reaction
Copper oxide Displacement Displacement

No reaction

2.) Which metals do not corrode easily?

Ans 2- Metals which are less reactive do not corrode easily.

Eg- Gold and silver

3.) What are alloys?

Ans3- It is a homogeneous mixture of two or more metals or a metals and non- metals  is called alloy.

E.g: When iron is mixed with chromium and nickel it forms stainless steel.

Exercise:

1.) 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.

Ans1-  d) AgNO3 solution and copper metal

Reason: Copper is more reactive than silver. So it will displace the silver from its solution.

 

2.) Which of the following methods is suitable for preventing an iron frying pan from rusting?

(a) Applying grease

(b) Applying paint

(c) Applying a coating of zinc

(d) All of the above.

Ans2- e) Applying coating of Zinc

Reason: Coating of thin layer of Zinc on iron or steel to prevent it from rusting. The process is known as galvanisation.

 

3.) An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

(a) calcium (b) carbon (c) silicon (d) iron.

Ans3- a) Calcium

Reason: It reacts with oxygen to form Calcium Oxide or quick lime. It has high melting point. Also, soluble in water i.e

CaO+ H2O → Ca(OH)2

 

4.) Food cans are coated with tin and not with zinc because

(a) zinc is costlier than tin.

(b) zinc has a higher melting point than tin.

(c) zinc is more reactive than tin.

(d) zinc is less reactive than tin.

Ans 4- c) Zn is more reactive than tin.

Reason: As Zinc is more reactive, so if food items cans are coated with it, it may react with food items and cause problems to human body.

 

5.) You are given a hammer, a battery, a bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?

Ans5- a) Beating the sample with hammer, if it get easily converted into sheet then it is a metal.

(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

b) The teat are based on physical properties and no chemical reactions have been involved.

Alternative Answer –

a.) Metals are converted into sheets by hammering because metals are malleable compared to non metals whereas non metals are broken by hammering. When we hit the metals it form any other shape without breaking. In this reason metals are called malleable.

b.)

First we connect battery, bulb,wire and switch as shown in the figure,and put metal in between the A and B then we notice that the bulb will start glowing because metals are good conductors, whereas when we put non metal in between the A and B then we notice that bulb will not glowing, because non metals are very poor conductors and non metals are not have the capacity to flow electric charges through them.

 

6.) What are amphoteric oxides? Give two examples of amphoteric oxides.

Ans 6- Those oxides which shows both acidic as well as basic behaviour and reacts with both acids and bases to produce salt and water are known as Amphoteric Oxides.

Eg: Aluminium oxides, Zinc Oxide

Alternative Answer –

When a metal react with oxygen or when a metal react with  both acids and bases after chemical reaction it will gives salt and water in the form of basic oxides then it is known as amphoteric oxides.

Ex: Aluminium,Tin

  • Al2O3 + 2NaOH → 2NaAlO2 + H2O
  • SnO + 2HCl → SnCl2 +H2O

 

In case you are missed :- Previous Chapter Solution

 

7.) Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Ans 7- • Two metals which will displace hydrogen from dilute acid are : Magnesium and Iron

  • Two metals which will not displace hydrogen from dilute acid solutions are: Silver, Mercury.

Alternative Answer –

Two metals which will displace hydrogen from dilute acids are Aluminium and Iron.

Two metals which will not displace hydrogen from dilute acids are Silver and gold.

 

8.) In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Ans 8- Impure metal M  at anode and a thin strip of pure metal M at cathode and a salt solution of M metal as a electrolyte.

Alternative Answer –

The process of electrolytic refining, if metal is M then an anode is an a impure metal and an cathode is an thin strip of pure metal and electrolyte is an a solution of metal salt.

 

9.) Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

(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.

Ans 9 a) i) There will be no action of gas on dry litmus paper as they both lack moisture.

ii) Moist litmus paper turns into red

b) S(s) + O2(g) → SO2(g)

Alternative Answer –

When Sulphur react with oxygen in presence of heat after chemical reaction it gives Sulphur dioxide.

(i) there is no change in dry litmus paper because the Sulphur dioxide is already present in natural air.

(ii) When we put moist litmus paper in the contact of Sulphur dioxide it will turn blue moist litmus red due to its acidic nature.

Sulphur (s)+ Oxygen (g) → Sulphur dioxide (g)

S + O → SO2

 

10.) State two ways to prevent the rusting of iron.

Ans 10- Two ways to prevent the rusting of iron are:

i) Galvanisation: coating of thin layer of Zinc on steel or iron

ii) By painting.

Alternative Answer –

When iron react with oxygen it becomes ferric oxide or rust and because of this rusting iron will loose it’s strength. To prevent the iron from the rusting we can apply oil and paint. When we apply oil or paint on iron, the iron does not come in direct contact with oxygen.

 

11.) What type of oxides are formed when non-metals combine with oxygen?

Ans 11- Generally, Non-metal oxides are acidic oxides and neutral oxides.

  • Reaction of Acidic oxides: S(s) + O2(g) → SO2(g)
  • Reaction of Neutral oxides: 2H2(g) + O2(g) → 2H2O(l)

Alternative Answer –

When non metals are combine with oxygen after the reaction it gives acidic oxides.

 

12.) Give reasons

(a) Platinum, gold and silver are used to make jewellery.

(b) Sodium, potassium and lithium are stored under oil.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Ans 12- a) They are lustrous in appearance with malleability and ductility. Also, highly resistant to corrosion.

b) Sodium, potassium and Lithium are highly reactive metal which catches fire vigorously when exposed to air. Therefore, they are stored under oil.

c) Aluminium is highly reactive metal but it forms a non reactive layer of Aluminium oxide(Al2O3) by reacting with oxygen. So tis layer prevents it from further reaction. Moreover, it is a good conductor of heat.

d) It is easier to reduce metal oxides as compare to the metal sulphides and carbonates during the process of extraction.

Alternative Answer –

  • Because the platinum, gold and silver jewellery are look like very shiny and beautiful and it does not have any side effect on the wearer.
  • Because sodium, potassium and lithium when these metals are contact with water or oxygen it react vigorously, to prevent this reaction we store the sodium, potassium and lithium under the oil.
  • Because Aluminium is a good conductor of heat. And light metal also and cheap in cost. When Aluminium react with oxygen after the reaction it become Alluminium oxide, which makes a thin layer on the metal surface which prevents from the harmful reaction of the Aluminium. And normally Aluminium does not have any side effect on the Aluminium utensils.
  • Usually carbonate and sulphide ore are present in nature. During the process of extraction of oxides, metal can be obtaine esely. And sulphide ore react with air in presence of heat it converted into oxides. Comparing to sulphides and carbonates we can obtain metal easily from oxide.

 

13.) You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Ans 13- Copper reacts with atmospheric carbon dioxide and form a layer of copper carbonate i.e of green colour and loses it brown shiny surface. Washing the copper vessel surface with sour substances such as  lemon helps to regain its lustre by dissolving the layer and neutralising the base.

Alternative Answer –

When we buy a new copper metallic item it look like very shiny, but after some time a thin green coloured lyare will be formed on the copper metallic item because when copper is react with carbon dioxide (which is already present in air ) and moisture with time after the reaction copper carbonate will be formed for this reaction copper will loose it’s strength and shineness. To prevent from this reaction we use lemon or tamarind juice, because lemon and tamarind juice contain the citric acid. When we apply citric acid on the lyare, the lyare of copper carbonate will be vanished and the item which is made from copper metal will become shinefull again. Because of that copper vessel being cleaned with lemon or tamarind juice.

 

14.) Differentiate between metal and non-metal on the basis of their chemical properties.

Ans 14-

Metals

Non-Metals

Metal oxides are basic in nature. They are acidic in nature.
They are electropositive. They are electronegative
They react with water to form oxides and hydroxides. They do not react with water.
Their chlorides are ionic in nature. They are covalent in nature.

Alternative Answer –

                            Metals                        Non metals
1.    When metals are react with chlorine after reaction it will gives ionic metal chlorides. When non metals are react with chlorine after reaction it will gives covalent chlorides.
2.    Mg,Ca,Na,K are some metals are react with hydrogen after reaction it will gives metal hydrides. When non metals are react with hydrogen after reaction it will gives covalent hydrides.
3.    When metals are react with oxygen after reaction it will gives metal oxides. When non metals are react with oxygen after reaction it will gives acidic oxides.
4.    When metals are react with water after reaction it will gives metal hydroxide and Hydrogen gas. Non metals do not react with water.
5.    Metals are considered as electro positive. Non metals are considered as electro nagetive.

 

15.) A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Ans 15- The goldsmiths had used Aqua regia i.e. Royal water. A mixture of concentrated  Hydrochloric acid and conc. Nitric acid in the ratio 3:1. It is able to dissolve the gold.  Therefore, the outer layer of gold bangles get dissolved in aqua regia. So their weight was reduced drastically.

Alternative Answer –

When we add concentrate hydrochloric acid to concentrate nitric acid in the ratio of 3:1, after a chemical reaction it will gives Aqua regia. It is a special chemical which contains the power to disolve the nobel metals like gold and platinum. In the above case the man use Aqua regia solution to disolve the gold of the gold bangles. That’s why the bangles sparkled like new but their weight was reduced drastically.

 

16.) Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Ans16- It is because copper does not react with hot, cold water  or steam whereas iron reacts with steam. A steel an alloy of iron, so iron will reacts with the steam and formed the iron oxides (Fe3O4).

Alternative Answer –

When iron is react with steam which is produced by hot water after the reaction corrod will be formed. When corrode will form then iron will loose it’s strength but in this case, the copper does not react with water or steam. When temperature is change iron is effected whereas copper does not effect by the change in temperature because of that copper is used make hot water tanks and not steel.

In case you are missed :- Next Chapter Solution

Updated: April 17, 2023 — 2:39 pm

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