Class X Science / Metals and Non-Metals

Class X Science
Notes for Metals and Non-Metals

Elements are classified into two basic categories, metals and non-metals.

Before giving the definition of metal and non-metal, we must know some important terms:

(i) Malleability: Ability of an element due to which it can be beaten with hammer into thin sheets.

(ii) Ductility: Ability of an element due to which it can be drawn into wires.

(iii) Sonorous: Property of an element to produce sound when it is struck with a hard substance.

(iv) Brittleness: Property of an element to break easily into pieces on hammering or stretching.

Class X Science
NCERT Solution for Metals and Non-metals

NCERT IN-TEXT QUESTIONS SOLVED

1. Give an example of a metal which

(i) is a liquid at room temperature.

(ii) cart be easily cut with knife.

(iii) is the best conductor of heat.

(iv) is a poor conductor of heat.

Ans. (i) Mercury (Hg)

(ii) Sodium and potassium

(iii) Silver and copper

(iv) Lead -.

2. Explain the meanings of malleable and ductile.

Ans. Malleable: A metal is said to be malleable if it can be beaten into thin sheets, e.g. silver and gold are the best malleable metals.

Ductile: A metal is said to be ductile when it can be drawn into thin wires, e.g. silver and gold are the best ductile metals.

3. Why is sodium kept immersed in kerosene oil?

Ans. Sodium is highly reactive metal. It reacts with oxygen in air at room temperature, the reaction is highly exothermic. To prevent this sodium is kept preserved under kerosene. Sodium does not react with kerosene.

4. Write equations for the reactions of

(i) iron with steam

(ii) calcium and potassium with water

Ans. (i) Iron with steam

5. Samples of four metals A,B, C and D were taken and added to the following solutions 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 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?

Ans. (i) B is most reactive.

(ii) Blue colour of copper sulphate solution disappears’ arid-reddish brown copper metal is deposited on the metal B.

(iii) B > A > C > D is the order of reactivity.

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

Ans. When a reactive metal reacts with hydrochloric acid hydrogen gas is produced A reactive metal displaces the hydrogen from acid and release hydrogen gas.

Fe(s) .+ dil H2SO4(aq) → FeSO4(aq) + H2(g)

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

Ans. Zinc is more reactive than iron, hence when added‘ to iron (II) sulphate, it can displace iron metaliand the colour of solution fades from green to colourless due to formation of zinc sulphate. The greyish black iron metal gets deposited.

8. (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?

9. Why do ionic compounds have high melting points?

Ans. Ionic compounds are made up of two opposite charged ions i.e., cations (+) and anions (ï¿½), which are held together with strong electrostatic force of attraction. To break this strong bonding into ions, large amount of heat energy is required, hence the melting point of ionic compounds is high.

10. Define the following terms:

(i) Mineral (ii) Ore (iii) Gangue

Ans. (i) Mineral: The naturally occurring chemical substance which ,contains metals with, some other elements: or impurities is called mine*,

(ii) Ore: The minerals from which metals can be extracted economically on large scale are called ores.

(iii) Gangue: The impurities present in ore/minerals are called gangue.

11. Name two metals which are found in nature in free state.

Ans. Gold, platinum and silver.

12. What chemical process is used for obtaining a metal from oxide?

Ans. To obtain metals from its oxides for metals of medium reactivity one can use carbon as reducing agent and the chemical process is called reduction. Also; displacement reaction is used in which highly reactive metal acts as reducing agent. !But for the metals of high reactivity the method of electrolytic reduction in used.

e.g., 3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(s) + heat

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

In which cases will you find displacement reactions take place?

Ans.

14. Which metals do not corrode easily?

Ans. Metals which are less reactive and lie at the bottom of reactivity series i.e., silver, gold, platinum do not react with atmospheric gases and hence do not corrode easily.

15. What are alloys?

Ans. Alloys are homogeneous mixture of two or moreï¿½ metals or metals or metal and non-metal.

e.g., Brass ï¿½ Cu + Zn

metal + metal

Bronze ï¿½ Cu + Zn

metal + metal

Steel ï¿½ Fe + Ni + Cr + C

metals + non-metal

QUESTIONS FROM NCERT TEXTBOOK

1. Which of the following pairs will give displacement reactions?

(a) NaCl solution and copper metal (b) MgCI2 solution and aluminium metal

Ans. (a) Cu cannot displace Na → No reaction

(b) Al cannot displace Mg → No reaction

(d) Cu can displace Ag → Reaction takes place

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

(a) Applying grease (b) Applying paint

Ans. (c) Applying a coating of zinc

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

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

Ans. (a) Calcium.

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

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

Ans. (c) zinc is more reactive, than tin.

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

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

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

Ans. (a) To distinguish between samples-of- metals and non-metals one can use hammer to beat the given material into sheets, if it breaks it is non-metal but if it is beaten into thin sheets it is a metal.

One can also use battery, wires, bulb and switch to make a circuit and use the given material to complete the circuit one by one, if the electric current flows and the bulb glows then it is metal and if not then it is non-metal.

(b) Though these tests gives us rough ideas in distinguishing between metals and non-metals but they are not reliable because both in metals & non-metals there are exceptions. For example Na metal is brittle and graphite can show conductivity.

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

Ans. The oxides which behave as acid as well as base are called amphoteric oxides e.g., Al2O3 and ZnO are amphoteric oxides; they both react with acid as Well as base to give salt and water.

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

Ans. Metals which lie above Hydrogen in the activity series ie. Zn, Al, Mg can displace hydrogen from dilute acids, because they are more reactive than H2. Metals which lie below hydrogen in the activity series i.e. Cu, Ag, Au cannot displace hydrogen from dilute acids, because they are less reactive than hydrogen.

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

Ans. For electrolytic refining of M:

Impure metal M → will be anode

Pure sample of M → will be cathode

Electrolyte → Acidified, soluble salt of metal M

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 the balanced chemical equation for the reaction taking place.

Ans. (a) (i) There will be no effect of gas on dry litmus paper.

(ii) Moist blue litmus paper turns red.

(b) (i) S + O2 → SO2

(ii) SO2 + H2O → H2SO3

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

Ans. (i) Rusting can be prevented by painting iron articles so that iron surface does not come in contact with air and moisture required for rusting.

(ii) By coating iron articles with a protective layer of zinc metal i.e. by galvanization which prevents the rusting of iron.

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

Ans. When non-metals combine with oxygen they form acidic oxides. E.g. SO2, CO2, NO2. [In some cases it also form neutral oxide e.g., H2O, CO]

12. Give reasons:

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

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

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

Ans. (a) Au, Ag and Pt are highly lustrous, malleable and ductile, so. they are used in making jewellery.

(b) Na, K and Li are highly reactive matals, they react with oxygen present in air at room temperature and catches ï¿½fire in presence 8foistuï¿½re. They donï¿½t react with oil (kerosene), hence stored in oil.

(c) Aluminium form a very protective layer of Aluminium (Al2O3) oxide on its surface which protects it from corrosion (or reaction with any food item).

(d) Reduction of metal oxides to metal is cheaper and easier than the reduction of carbonate and sulphide ores. So carbonate and sulphide ores are first converted to metal oxide and then further reduced to form metals.

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 vessel?

Ans. Copper metal corrodes to form copper carbonate and get tarnished. On cleaning with lemon or tamarind juice, the acid present in: them dissolves the copper carbonate thereby cleaning the vessel.

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

Ans.

Metal	Non-metal
1. Metals loose electrons .to form positive ions.	Non-metals gain electrons to form negative -ions.
2. Metals fon basic oxides.	Nonmetals form acidic oxides.
3. Metals scan displace hydrogen from acids.	Non-metals cannot displace hydrogen from acids.
4. All metals do not combine with hydrogen to form hydrides (except reactive metals like Na, K, Ca).	All non-metals combine with hydrogen to form hydrides.

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. The solution is aqua regia (1 part of conc. HNO3 acid and 3 part of conc. HCl acid) is used by the goldsmith, which dissolves gold.

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

Ans. Copper is a good conductor of heat as compared to steel.

MULTIPLE CHOICE QUESTIONS
METALS AND NON-METALS

1. Which of the following metals is present in the anode mud during the electrolytic refining of copper?

(a) Sodium (b) Aluminium (c) Gold (d) Iron

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

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

3. The second most abundant metal in the earth’s crust is

(a) oxygen (b) silicon (c) aluminium (d) iron

4. An alloy of Zn and Cu is dissolved in dil. HC1. Hydrogen gas is evolved. In this evolution of gas

(a) only zinc reacts with dil. HC1 (b) only copper reacts with dil. HC1

5. A greenish coating develops on copper utensils due to formation of

(a) CuCo3 (b) Cu(OH)2 (c) Cu(OH)2.CuCO3 (d) CuO

6. Rusting of iron takes place in

(a) ordinary water (b) distilled water

7. The bronze medals are made up of

(a) Cu and Zn (b) Zn and Ni (c) Cu and Sn (d) Cu, Zn, Tn

8. Silver articles becomes black on prolonged exposure to air. This is due to the formation of

(a) Ag2O (b) Ag2S (c) AgCN (d) Ag2O and Ag2S

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9. During smelting, an additional substance is added which combines with impurities to form a fusible product known as

(a) slag (b) mud (c) gangue (d) flux

10. A student placed an iron nail in copper sulphate solution. He observed the reddish brown coating on the iron nail which is

(a) soft and dull (b) hard and flading (c) smooth and shining (d) rough and granular

11. Which among the following alloys contain non-metal as one of its constituents?

(a) Brass (b) Amalgam (c) Gun metal (d) None of these

12. An aluminium strip is kept immersed in freshly prepared ferrous sulphate solution taken in a test tube, the change observed is that

(a) Green solution slowly turns brown

(b) Lower end of test tube become slightly warm

(d) Light green solution changes to blue.

Answers

1. (d) 2. (c) 3. (d)

4. (a) 5. (a) 6. (c) 7. (c) 8. (b)

9. (a) 10. (d) 11. (b) 11. (a)

Previous Year Questions
Metals and Non-Metals

1. Name a reducing agent that may be used to obtain manganese from manganese dioxide. (CBSE 2009)

2. From amongst the metals sodium, calcium, aluminium, copper and mangnesium, name the metal (I) which reacts with metal only on boiling and

(II) another which does not react even with steam. (CBSE 2008)

3. (a) Show the formation of NaCl from sodium and chlorine atoms by the transfer of electrons.

(b) Why sodium chloride has a high melting point?

Why are ionic compounds usually hard? How is it that ionic compounds in the solid state do not conduct electricity but they do so when in molten state? (CBSE 2008)

On adding dilute HCL acid to copper oxide powder the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution. (CBSE 2008)

4. (a) Show on a diagram the transfer of electron between the atoms in the formation of MgO.

(b) Name the solvent in which ionic compounds are generally soluble.

5. What are amphoteric oxides? Choose the amphoteric oxides from- Na2O, ZnO, Al2O3, CO2, H2O

6. Why is it that non-metals do not displace hydrogen from dilute acids? (AI CBSE 2008)

7. Show the electronic transfers in the formation of MgCl2 from its elements. (CBSE 2008 F)

8. Which of the following metals will melt at body temperature: gallium, magnesium, caesium, aluminium? (CBSE 2008 C)

9. Name the two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any? (AI CBSE 2008)

10. Give reasons for the following: (i) Gold and silver are used for jewellery making.

(ii) carbonate and sulphide ores are usually converted into oxides prior to reduction during the process of extraction. (CBSE 2008 C)

11. Give reasons for the following: (i) Aluminium oxide is considered as an amphoteric oxide.

(ii) Ionic compounds conduct electricity in molten state. (CBSE 2008 C)

12. Give reasons for the following:

(i) Metals can be given different shapes according to our needs.

(ii) Hydrogen is not evolved when a metal reacts with nitric acid.

HIGHER ORDER THINKING SKILLS QUESTIONS
METALS AND NON-METALS

1. A metal ‘X’ loses two electrons and a non-metal ‘Y’ gains one electron. Show the electron dot structure of compound formed between them. Is ionic or covalent? Does it have high melting point or low? Will it conduct electricity in solid state or in aqueous solution and why? Will it be soluble in water?

2. A student was given Mn, Zn, Fe and Cu metals. Identify which of them

(a) will not displace H2 from dil. HCl.

(b) will react only with steam to give H2(g).

Write the chemical reactions involved.

3. Compound X and aluminium are used to join railway tracks.

(a) Identify the compound X.

(b) Name the reaction.

4. Samples of five metals ‘A’, ‘B’, ‘C’, ‘D’ and ‘E’ were taken and added to the following solution one

by one. The results obtained have been tabulated as follows.

Metal FeSO4 CuSO4 ZnSO4 AgNO3 Al2(SO4)3 MgSO4

A No reaction Displacement No reaction Displacement No reaction No reaction

B Displacement Displacement No reaction Displacement No reaction No reaction

C No reaction No reaction No reaction Displacement No reaction No reaction

D No reaction No reaction No reaction No reaction No reaction No reaction

E Displacement Displacement Displacement Displacement No reaction No reaction

Use the above table to answer the following questions about the given metals.

(a) Which of them is most reactive and why?

(b) What would you observe if ‘B’ is added to CuSO4?

(d) Container of which metal can store zinc sulphate and silver nitrate solution?

(e) Which of the above solution(s) can be stored in a container made of any of these metals and

why?

5. A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is

amphoteric in nature? Identify A and B. Write down the reactions of oxide B with HC1 and NaOH.

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6. 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.

(a) Identify A, B and C.

(b) To which group of periodic table does A belong?

7. 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 which on treatment with water gives back B. Identify A, B and C and

give the reactions involved.

8. A non-metal A which 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 and acid D which act as a strong oxidising agent.

(a) Identify A, B, C and D.

(b) To which group of periodic table does this non-metal belong?

9. 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.

TEST FOR METALS AND NON-METALS

MAX TIME: 45 mins

MAX MARKS: 20

1. Fill in the blanks

(1 ï¿½ 5 = 5 marks)

a. Cu2S acts as ______ agent in Bassemerisation process.

b. CaSiO3 is known as _______ in extraction of iron.

c. SO2 is the product of ________ of sulphide ores.

d. ZnO can be reduced by ________.

e. ________ forms greenish layer due to basic copper carbonate.

2. Why can Zn replace hydrogen from dil. HCl?

(2 marks)

3. a. Show on a diagram the transfer of electrons between the atoms in the formation

of MgO. Write symbols of cation and anion present in MgO.

(2 marks)

4. Why do non-metals not conduct

electricity? Also, name one non-metal that conducts electricity.

(3 marks)

5. Write balanced chemical equations for the following:ï¿½

(3 marks)

a. Dilute sulphuric acid reacts with aluminium powder.

b. Dilute hydrochloric acid reacts with sodium carbonate.

c. Carbon dioxide is passed through lime water.

6. Give the steps involved in the extraction of metals of low and medium reactivity from

their respective sulphide ores.

(5 marks)

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