CHAPTER 3 Metals and Non metals KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS

CHAPTER 3 Metals and Non metals KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS English medium Karnataka state board 2024,the Answers Are Prepared By Our Teachers Which Are Simple ,Pointwise,Easy To Read And Remember ,

CHAPTER 3 Metals and Non metals KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS

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 hea

ANSWER:-

(i) is a liquid at room temperature.

– Mercury

(ii) can be easily cut with a knife.

– Sodium

(iii) is the best conductor of heat.

– Silver

(iv) is a poor conductor of heat.

– Lead

2.Explain the meanings of malleable and ductile:

ANSWER:-

- Malleable: Ability of a metal to be hammered or pressed into thin sheets without breaking.
- Ductile: Ability of a metal to be drawn into thin wires without breaking.

3.Why is sodium kept immersed in kerosene oil?

ANSWER:-

Sodium is kept immersed in kerosene oil because it reacts vigorously with oxygen in the air, potentially causing fires. By keeping it immersed in kerosene oil, it is protected from oxygen and accidental fires.

4.Write equations for the reactions of:

(i) iron with steam

ANSWER:-

Iron + Steam → Iron(II) oxide + Hydrogen

(ii) calcium and potassium with water

ANSWER:-

Calcium + Water → Calcium hydroxide + Hydrogen

Potassium + Water → Potassium hydroxide + Hydrogen

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.

Metal Iron(II) sulphate Copper(II) sulphate Zinc sulphate Silver nitrate

A No reaction Displacement

B Displacement No reaction

C No reaction No reaction No reaction Displacement

D No reaction No reaction No reaction No reaction

Use the table above to answer the following questions about metals A, B, C, and D:

(i) Which is the most reactive metal?

ANSWER:-

Metal B is the most reactive because it displaced iron from iron(II) sulphate solution and displaced copper from copper(II) sulphate solution.

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

ANSWER:-

Metal B would displace copper from copper(II) sulphate solution, resulting in a displacement reaction where B replaces Cu. This would lead to the formation of metal B sulphate solution and copper metal.

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

ANSWER:-

Most reactive: B
Second most reactive: D (since it displaced silver from silver nitrate solution)
Third most reactive: A (since it displaced iron from iron(II) sulphate solution)
Least reactive: C (since it did not displace any metal from any solution)

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.

ANSWER:-

Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.
Chemical reaction when iron reacts with dilute H2SO4:

Iron + Dilute H2SO4 → Iron(II) sulfate + Hydrogen gas

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

ANSWER:-

When zinc is added to a solution of iron(II) sulphate, you would observe displacement, with zinc displacing iron from the solution.
Chemical reaction:

Zinc + Iron(II) sulphate → Zinc sulphate + Iron

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

ANSWER:-

Sodium: Na •
Oxygen: O ••
Magnesium: Mg ••

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

ANSWER:-

EXTRA INFORMATION:-

Formation of Na2O:

Sodium (Na) loses one electron to form Na+ ion: 2Na → 2Na+ + 2e^-
Oxygen (O) gains two electrons to form O2- ion: O + 2e^- → O2-
Na+ and O2- ions combine to form Na2O: 2Na+ + O2- → Na2O

Formation of MgO:

Magnesium (Mg) loses two electrons to form Mg2+ ion: Mg → Mg2+ + 2e^-
Oxygen (O) gains two electrons to form O2- ion: O + 2e^- → O2-
Mg2+ and O2- ions combine to form MgO: Mg2+ + O2- → MgO

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

ANSWER:-

Na2O: Sodium ions (Na+) and oxide ions (O2-)
MgO: Magnesium ions (Mg2+) and oxide ions (O2-)

2.Why do ionic compounds have high melting points?

ANSWER:-

Ionic compounds have high melting points because they consist of a three-dimensional lattice structure held together by strong electrostatic forces of attraction between oppositely charged ions.
Breaking these strong inter-ionic attractions requires a considerable amount of energy, which leads to high melting points for ionic compounds.

1.Define the following terms.

(i) Mineral

(ii) Ore

(iii) Gangue

ANSWER:-

Definitions:

(i) Mineral:Naturally occurring elements or compounds in the Earth’s crust.

(ii) Ore: Minerals containing a high percentage of a particular metal, from which the metal can be profitably extracted.

(iii) Gangue: Impurities such as soil, sand, etc., present in ores, which must be removed before extracting the metal.

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

ANSWER:-

Two metals found in nature in the free state are gold and silver.

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

ANSWER:-

The chemical process used for obtaining a metal from its oxide is reduction. In this process, the metal oxide is heated with a reducing agent such as carbon, which removes oxygen from the oxide, leaving behind the pure metal. Displacement reactions and electrolytic reduction are also used for obtaining metals from their oxides, depending on their reactivity.

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

Metal	Zinc	Magnesium	Copper
Zinc oxide
Magnesium oxide
Copper oxide

In which cases will you find displacement reactions taking place?

ANSWER:-

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

Zinc oxide + Magnesium: Displacement reaction will occur.
Magnesium oxide + Copper: Displacement reaction will occur.
Copper oxide + Zinc: Displacement reaction will occur.

In each case, the more reactive metal will displace the less reactive metal from its oxide, resulting in the formation of new compounds. This phenomenon is known as a displacement reaction.

2.Which metals do not corrode easily?

ANSWER:-

Metals that do not corrode easily include:

Gold
Silver
Platinum
Stainless steel (alloy of iron, chromium, and nickel)

3.What are alloys?

ANSWER:-

Alloys are:

Homogeneous mixtures of two or more metals, or a metal and a non-metal.
Prepared by melting the primary metal and then dissolving other elements in definite proportions.
Examples include brass (copper and zinc), bronze (copper and tin), and stainless steel (iron, chromium, and nickel).

EXERCISES

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

a) NaCl solution and copper metal

(b) MgCl2 solution and aluminium metal

(d) AgNO3 solution and copper metal.

ANSWER:-

(d) AgNO3 solution and copper metal.

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

(a) Applying grease

(b) Applying paint

d) All of the above.

ANSWER:-

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

(d) iron.

ANSWER:-

(a) calcium.

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.

(d) zinc is less reactive than tin

ANSWER:-

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?

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

ANSWER:-

(a) To distinguish between samples of metals and non-metals:

Metals can be tested for their ability to conduct electricity using the battery, bulb, wires, and switch (circuit formation).
Non-metals can be tested for their inability to conduct electricity, breaking easily with the hammer.

(b) These tests are useful because they rely on fundamental properties of metals and non-metals – conductivity and malleability

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

ANSWER:-

Amphoteric oxides are compounds that exhibit properties of both acidic and basic oxides. Two examples of amphoteric oxides are:

Aluminium oxide (Al2O3)
Zinc oxide (ZnO)

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

ANSWER:-

Metals that will displace hydrogen from dilute acids:

Zinc (Zn)
Iron (Fe)

Metals that will not displace hydrogen from dilute acids:

Copper (Cu)
Silver (Ag)

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

ANSWER:-

In the electrolytic refining of a metal M:

Anode: Impure metal M
Cathode: Pure metal M
Electrolyte: A solution containing ions 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 a balanced chemical equation for the reaction taking place.

ANSWER:-

(a)

Dry litmus paper: No significant action.
Moist litmus paper: Turns moist litmus paper red (indicating an acidic gas).

(b) Balanced chemical equation:

S(s) + O2(g) -> SO2(g)

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

ANSWER:-

Two ways to prevent the rusting of iron:

Applying a coating of paint or oil.
Galvanizing the iron by applying a layer of zinc.

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

ANSWER:-

Non-metals combine with oxygen to form acidic oxides.

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.

ANSWER:-

(a) Platinum, gold, and silver are used to make jewellery because they are highly lustrous, malleable, and do not corrode easily.

(b) Sodium, potassium, and lithium are stored under oil because they react vigorously with air and water, which can lead to fires or explosions.

(c) Aluminium is used to make utensils for cooking despite being highly reactive because it forms a protective oxide layer on its surface, preventing further reaction with air or water.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because oxides are easier to reduce to obtain the pure metal

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.

ANSWER:-

Sour substances like lemon or tamarind juice are effective in cleaning tarnished copper vessels because they contain acids (citric acid in lemon, tartaric acid in tamarind) which react with the tarnish (copper oxide) to form soluble compounds, making it easier to remove the tarnish and restore the shine.

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

Metals tend to form positive ions (cations) by losing electrons, whereas non-metals tend to form negative ions (anions) by gaining electrons.
Metals generally react with oxygen to form basic oxides, while non-metals react with oxygen to form acidic or neutral oxides.
Metals have low electronegativity and tend to lose electrons easily, while non-metals have high electronegativity and tend to gain electrons easily.
Metals typically react with dilute acids to produce hydrogen gas, while non-metals do not react with dilute acids to produce hydrogen gas.

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?

ANSWER:-

The solution used by the man was likely a mixture of gold and other metals dissolved in a strong acid, such as aqua regia (a mixture of nitric and hydrochloric acids). This solution would dissolve the gold, leaving behind other metals, thereby reducing the weight of the bangles while maintaining their appearance

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

ANSWER:-

Copper is used to make hot water tanks instead of steel because:

Copper has better thermal conductivity than steel, allowing for faster heating of water.
Copper is more resistant to corrosion in hot water compared to steel.
Copper is malleable, allowing for easier shaping of the tank without compromising its structural integrity.