KSEEB Solutions for Class 10 Science Chapter 3 Metals and Non-metals

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Karnataka State Syllabus Class 10 Science Chapter 3 Metals and Non-metals

KSEEB Class 10 Science Metals and Non-metals Intext Questions and Answers

Question 1.
Give an example of a metal which

i) is a liquid at room temperature
Answer:
Mercury

ii) Can be easily cut with a knife
Answer:
Sodium

iii) Is the best conductor of heat
Answer:
Silver

iv) Is a poor conductor of heat
Answer:
Lead

Question 2.
Explain the meanings of malleable and ductile?
Answer:

1. Malleable: Some metals can be beaten into thin sheets. This property is called Malleability.
2. Ductility: The ability of metals to be drawn into thin wires is called ductility.

Question 3.
Why is sodium kept immersed in Kerosene oil?
Answer:
Sodium is a very reactive metal. It reacts vigorously with the water and oxygen present in air and even catches fire. Hence, to protect sodium, it is kept immersed in Kerosene oil.

Question 4.
Write equations for the reactions of
(a) Iron with stream
(b) Calcium and potassium with water.
Answer:
(a) 3 Fe(s) + 4 H₂O(g) → Fe₃O4(s) + 4 H₂(g)
(b) Ca(s) + 2 H₂O (I) → Ca (OH)₂(aq) + H₂(g)
2K(s) + 2H₂O(l) → 2KOH (aq) + H₂(g)

Question 5.
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 below to answer the following questions about metals A, B, C and D.

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

(i) Which is the most reactive metal?
Answer:
B is most reactive

(ii) What would you observe, if B is added to a solution of copper (II) sulphate?
Answer:
B will displace copper from copper (II) sulphate.

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

Question 6.
Which gas is produced, when dilute HCL is added to a reactive metal? Write the chemical equation, when iron reacts with dil. H₂SO₄?
Answer:
Hydrogen gas is produced when a metal reacts with HCl.

Question 7.
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, the greenish colour of iron II sulphate solution fades away gradually, due to the formation of colourless zinc sulphate solution Iron metal is deposited on zinc.

Question 8.
i) Write the electron dot structures of sodium, oxygen and magnesium.
ii) Show the formation of Na₂O and MgO by the transfer of electors.
iii) What are the ions present in these compounds
Answer:
(i)

(ii) Formation of Na₂O: The atomic number of sodium is 11 and it has only one valence electron. Hence electronic configuration of Na¹¹ is 2,8,1. The atomic no of oxygen is 8 and it has 6 electrons in its valence shell. Hence electronic configuration of O⁸ is 2,6.

Sodium has a tendency to lose the valence electron and oxygen has a tendency to gain the electron lost by sodium. Since, sodium can lose only one electron of the valence shell and oxygen atom needs two electrons to complete its octet in the valence shell, two atoms of sodium combine with one atom of oxygen. By losing valence electron, sodium is changed into Na⁺ and by gaining two electrons lost by two sodium atoms, oxygen atom is changed into an oxide anion.

O^2-. In this process both the atoms, sodium and oxygen obtain the stable electronic configuration of Neon.

The oppositely charged sodium ion, Na⁺ and oxide ion, O^2- are now held together by electrostatic forces of attraction or electron valent bond, Na₂O is, therefore, an ionic or electron valent compound.

Formation of MgO:

The atomic number of magnesium =12.
Its electronic configuration is K = 2, L = 8, M = 2.
It has two electrons in its outermost shell. So, the magnesium atom donates its 2 valence e’ns and forms a stable magnesium ion Mg²⁺, to attain the electronic arrangement of neon gas.

The atomic number of oxygen = 8 Electronic configuration ⇒ K = 2, L = 6
It has 6 electrons in its valence shell. Therefore it requires two more electrons to attain the stable electronic arrangement of neon gas. Thus oxygen accepts two electrons donated by magnesium atom and forms a stable ion O^2-

The oppositely charged magnesium ions, Mg²⁺ and oxide ions, O^2_ are held together by a strong force of electrostatic attraction. form magnesium oxide compound Mg²⁺ O^2- or MgO.

MgO is an ionic compound.
(iii) The ions present in Na₂O are sodium ions (2Na⁺) and oxide ion O^2-. The ions present in MgO are magnesium ion (Mg²⁺) and oxidation O^2-.

Question 9.
Why do ionic compounds have high melting points?
Answer:
The ionic compounds are made up of positive and negative ions. There is a strong force of attraction between the oppositely charged ions. Therefore a lot of energy is required to break this force of attraction and melt this ionic compound. That is why ionic compounds have high melting points.

Question 10.
Define the terms
(a) Mineral
(b) Ore
(c) Gangue.
Answer:
Mineral: The inorganic element or compound which occurs naturally in the earth’s crust is called a mineral. Ex: Copper pyrites, cuprite are the minerals of copper.

Ore: The mineral form which a metal can be extracted profitability and conveniently is called an ore.

Ex: Bauxite and clay are the minerals of aluminum. But extraction of aluminium is cheaper and easier from bauxite. Hence bauxite is the ore of aluminium.

Gangue or matrix: The unwanted impurities of sand and rocky materials present in the ore are known as gangue or matrix.

Question 11.
Name the 2 metals which found in nature in free state?
Answer:
Gold and silver are least reactive and hence these metals occur in nature in the free state.

Question 12.
What chemical process is used for obtaining a metal from it’s oxide?
Answer:
A metal can be extracted from its oxide by the process of reaction:
2HgO(s) \(\overset { heat }{ \rightarrow } \) 2Hg(l)+O₂ (g)

Question 13.
Metallic oxides of Zinc, magnesium and copper were heated with the following metals – Zinc oxide, magnesium oxide and copper oxide. In which case will you find, displacement reactions taking place.
Answer:
As we know, a more reactive metal can displace less reactive metal from its oxide. Here magnesium is the mast reactive. Zinc is less reactive where as copper is the least reactive metal. Thus displacement reactions will takes place in the following cases.

Metal	Zinc	Magnesium	Copper
Zincoxide	–	Displacement	–

 

Magnesium oxide	–	–	–
Copper oxide	Displacement	Displacement	–

Question 14.
Which metals do not corrode easily?
Answer:
Silver, gold, platinum and titanium

Question 15.
What are alloys?
Answer:
Alloys are homogeneous mixtures of, two or more metals, or a metal and a non metal
Ex:

• Brass is an alloy of copper and zinc.
• Steel is an alloy of iron and carbon.

KSEEB Class 10 Metals and Non-metals Textbook Exercise Questions and Answers

Question 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.
Answer:
(d) AgNO₃ solution and copper metal.

Question 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.
Answer:
(c) Applying a coating of zinc

Question 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
Answer:
(a) Calcium

Question 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.
Answer:
(c) zinc is more reactive than tin.

Question 5.
You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between simples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.
Answer:
(a) Hit the given substances with a hammer. If these are formed into thin sheets we call this is Malleability. Such a substance is metal. Otherwise, it is non-metals. Similarly, if battery, bulb, wire, and switch are connected and passed electric current, this substance is called metal. If not it is called non-metal.
(b) The above tests are helpful to find out the differences between metal and Non-metal. No chemical reactions.

Question 6.
What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer:
The oxides which react both with acids as well as bases to form salts and water are known as amphoteric oxides. Ex: aluminium oxide and zinc oxide.

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

• Metals like sodium and magnesium displace hydrogen from dilute acids (metals above hydrogen inactivity series)
• Metals below hydrogen in the activity series like copper, silver do not displace hydrogen from dilute acids.

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

• Cathode  – pure metal
• Anode  – Impure metal
• electrolyte –  Metal salt solution

Question 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.
Answer:

(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 reaction;
moist litmus paper – becomes red

Question 10.
State two ways to prevent the rusting of iron.
Answer:
Ways to prevent rusting of iron

• by painting
• by galvanising

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

Question 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.
Answer:
(a) Platinum, gold and silver are non reactive and give shining surface.
(b) Sodium, potassium and lithium are very reactive and catch fire when exposed to air.
(c) Aluminium forms a non reactive layer of aluminium oxide on its surface.
(d) It is easier to reduce oxides into metal.

Question 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:
Copper vessels get a green deposit of copper carbonate. Since copper arbonate dissolves in mild acids of lemon or tamarind juice, copper vessels are cleaned.

Question 14.
Differentiate between metal and non­metal on the basis of their chemical properties.
Answer:

Metals	Non-metals
a) They form basic oxides	a) They form acidic or neutral oxides.
b) They replace from acids and form salts	b) They do not replace hydrogen from acids.
c) With chlorine metals from chlorides which are electrovalent.	c) With chlorine non-metals from chlorides which are covalent
d) With hydrogen few metals form hydrides which are electrovalent.	d) With hydrogen non metals form many stable hydrides which are covalent.

Question 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:
Aqua regia – a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1 since it dissolves gold.

Question 16.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron),
Answer:
Iron (steel) reacts with hot water but copper does not.

Multiple-choice Questions:

Question 1.
The conductivity of metals. Al, Ag and Cu, increase in the order.
(a) Cu < Al < Ag
(b) Al < Ag < Cu
(c) Al < Cu < Ag
(d) Ag < Cu < Al
Answer:
(c) Al < Cu < Ag

Question 2.
Which of the following metals gives a black basic oxide on heating?
(a) Copper
(b) Mercury
(c) Iron
(d) Lead
Answer:
(a) Copper

Question 3.
An 18 carat gold contains
(a) 15% impuritues
(b) 25% impurities
(c) 30% impurities
(d) 40% impurities
Answer:
(c) 30% impurities

Question 4.
Which of the following metals liberate H₂ on reaction with dilute HNO₃?
(a) Zn
(b) Cu
(c) Mg
(d) Mn
Answer:
(d) Mn

Question 5.
Do the following compounds conduct electrify in aqueous solution which is a covalent compound?
(a) CaCl
(b) HCl
(c)MgO
(d) LiF
Answer:
(b) HCl

Choose the correct answer:

Question 1.
The metal easily cut with a knife is
(a) Gold
(b) Silver
(c) Sodium
(d) Copper
Answer:
(c) Sodium

Question 2.
School bells arc made of metal is ………………
(a) Malleability
(b) Sonorous
(c) ducticity
(d) None of these
Answer:
(b) Sonorous

Question 3.
Amphotexic oxides are the following
(a) NaOH
(b) KGH
(c) Ca(OH)₂
(d) Al₂O₃
Answer:
(d) Al₂O₃

Question 4.
Sulphur dioxide dissolve in water vapour to form
(a) Sulphurous acid
(b) Sulphuric acid
(c) Nitric acid
(d) phosphoric acid
Answer:
(a) Sulphurous acid

Question 5.
Hydrogen gas is not evolved when a metal reacts with nitric acid the reason is ……………..
(a) Weak acid
(b) Strong oxidising agent
(c) do not oxidise to produce water
(d) all the above
Answer:
(b) Strong oxidising agent

Question 6.
The electronic configuration of 2,8,2 is
(a) Neon
(b) Sodium
(c) Magnesium
(d) Calcium
Answer:
(c) Magnesium

Question 7.
Ionic compounds conduct electricity in the Molten state is___________
(a) Ions move freely
(b) Ions are not moved freely
(c) Ionic compounds are solid
(d) rigid structure
Answer:
(a) Ions move freely

Question 8.
Ores of Mercury
(a) Zinc blead
(b) Magnesium sulphide
(c) Cinnabar
(d) None of these
Answer:
(a) Zinc blead

Match the following:

1. Bauxite	a) Manganese
2. Haematite	b) Gold
3. Phyr dusite	c) Aluminium
4. Magnesite	d) Copper pyrites
	e) Iron
	f) Chromite
	g) Magnesium

Answer:

1. (c) Aluminium
2. (e) Iron
3. (a) Manganese
4. (g) Magnesium

Match the following:

A	B
1. Reacts with cold water	(a) iron
2. Forms amphoteric oxide	(b) Magnesium
3. Exist in liquid state at room temperature	(c) Aluminium
4. Best conductor of heat	(d) Sodium
	(e) Silver
	(f) Lead
	(g) Mercury

Answer:

1. (d) Sodium
2. (c) Aluminium
3. (g) Mercury
4. (e) Silver

KSEEB Class 10 Science Metals and Non-metals Additional Questions and Answers

Question 1.
What is a thermit reaction? State one use of this reaction?
Answer:
The reaction between iron (III) oxide Fe₂O₃ and aluminium gives out lots of heat. It is called the thermit reaction.

This displacement reaction is oxide used to joins railway tracks or cracked machine parts.

The heat given out in the reaction melts the iron formed, the mitome iron runs down between the tracks and welds them together.

Question 2.
Why shoaled the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them?
Answer:
It is easier to obtain metal from its oxide, as compared from its sulphides and carbonates. So prior to reduction sulphide ores are converted into oxides by roasting and carbonate ores by calcination.

Question 3.
What is 24 – Carat gold? How will you convert it into 18 – carat gold?
Answer:
24 carat gold is pure gold, pure gold is very soft and not suitable for making jewellery. Therefore, to increase its hardness, it is alloyed either with copper or silver. 18-carat gold is prepared by alloying 18 parts pure gold with 6 parts of either copper or silver.

Question 4.
What would happen to iron railings on the road, side if they are painted? Why does it happen so?
Answer:
If the iron railings on the road side is not painted, a brown rust would form on its surface because the moist air of the atmosphere reacts with iron to form brown flaky substance on its surface. The rust is hydrated iron oxide (Fe₂O₃ 2H₂O)

Question 5.
Why are food cans tin plated instead of zinc plated though zinc is cheaper than tin?
Answer:
Tin is less reactive than zinc. It is less likely to dissolve in the liquid stored in the food cans. Tin reacts only with powerful acids whereas zinc can easily react even with tomatoes, so it is not safe to store food in
zinc – plated cans.

Question 6.
Which chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction

Question 7.
Which metals will melt at body temperature?
Answer:
Gallium and Caesium will melt at body temperature (37° C).

Question 8.
Name two metals which do not react with water at all?
Answer:
Lead and Copper.

Question 9.
Non-metals can not displace Hydrogen from the acid.
Answer:
Because non-metals are aceptors.

Question 10.
Name A metal and non-metal.
(a) Which make Iron hard and strong.
(b) Which make a Amalgum.
(c) Which is used to galvanise, Iron articles.
(d) Which article when exposed to air form a black coating.
Answer:
a) Carbon
b) Mercury
c) Zinc
d) Silver

Question 11.
The reactivity series is a list of metals arranged in the order of their decreasing activity.
Answer:
K > Na > Ca > Mg > Al > Zn > Fe > Sn > pb > H > Cu > Hg > Ag > Au

Question 12.
Which atom is bigger Na or MgS. Why?
Answer:
Magnesium atom is the bigger.
Because the atomic no. of sodium = 11.
The atomic no. of Magnessium = 12.

Question 13.
In this reaction the substance that undergoes reduction is
(a) H₂
(b) Cu
(c) H₂O
(d) CuO
Answer:
(d) CuO

Question 14.
A solution reacts with crushed Egg shells to give a gas that turns lime water milky. The solutions contains
(a) NaCl
(b) HCl
(c) LiCl
(d) KCl
Answer:
(b) HCl

Question 15.
Study the following chemical reactions. The most reactive element is
Cu + 2Ag[NO₃]₂ ⇒ Cu[N0₃]₂ + 2Ag
pb + Cu[NO₃]₂ → pb[NO₃]₂ + Cu
Zn + pb[NO₃]₂ → Zn[NO₃]₂ + pb
a) Ag [silver]
b) pb[Lead]
c) Cu[Copper]
d) Zn[Zinc]
Answer:
d) Zn[Zinc]

Question 16.
The following gas is very near to the chlorine
(a) He
(b) Ar
(c) Ne
(d) Kr
Answer:
(b) Ar

Question 17.
Which of the following is used for dissolutions of Gold.
(a) Hydrochloride acid
(b) Sulphuric acid
(c) Nitric acid
(d) Aquaregia
Answer:
(d) Aquaregia

Question 18.
The substance that is reduced following chemical reaction is
MnO₂ + 4HCI → MnCl₂ + 2H_zO + Cl₂
(a) KCl
(b) MnO₂
(c) MnCl₂
(d) Cl₂
Answer:
(b) MnO₂

Question 19.
Which of the 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
Answer:
d) AgNO₃ solution and copper metal

Question 20.
Reactivity series of metals
This metals do not displace Hydrogen
from dilute acids.
platinum Gold Silver Mercury.
Copper
This metal displaces Hydrogen very slowly from the dilute acids
Lead
These metals displace hydrogen from dilute acids slowly
Tin
Nickel
Iron

Question 21.
Name the ores of following metals:
(a) Aluminium
(b) Iron
(c) Copper
(d) Manganese
(e) Chromium
(f) Magnesium
Answer:
(a) Bauxite
(b) Haematite, Magnetite
(c) Copper pyrites
(d) Pyrolusite
(e) Chromite
(f) Magnesite

Question 22.
Mention the constituents, uses of following Alloys:
1. Stainless steel
2. Invar steel
3. Nickel steel
4. Brass
5. Bronze
6. Solder
7. Duralunin
8. Alnico
Answer:

Constituents	Uses
1. Fe+C+Cr+Ni	Surgical Instrument
2. Fe+ C + Ni [Large quantity]	Measuring tape
3. Fe+C+Ni [small quantity]	Machinery parts
4. Cu + Zn	Utensils
5. Cu + Zn + Sn	Statues, Metals utensils
6. pb + Sn	Welding electrical wires
7. Al+Cu+Mn+Mg	Aeroplane body railway coaches, bus coaches
8. Ni + CO + Fe + A1	permanent magnets

Question 23.
Draw Actions of steam on a metal of Label the parts
Answer:

Question 24.
Draw Testing the Conductivity of a salt solution and label the parts.
Answer:

Question 25.
Draw Electrolytic refining of Copper and label the parts.
Answer:

Question 26.
Aluminium is highly reactive metal yet it is used to make utensils for cooking why
Answer:
Because

• It is lightweight
• Good conductor of heat and form an oxidised layer to prevent further oxidations.

Question 27.
Carbonate and Sulphide ores are usually converted into oxides during the process of extractions why.
Answer:
Because we can convert into metal very easily if it is in sulphide or Carbonate ores form.

Question 28.
Write the balanced equations for the reaction taking place when
a) Dilute Hydrochloric acid reacts with Iron filings.
b) Dilute Sulphuric acid with Zinc granules
c) Dilute Sulphuric acid reacts with aluminium powder
Answer:
(a) 3Fe + 2HCl → Fe₃CL + H₂ ↑
(b) Zn + H₂SO₄ → ZnSO₄ + H₂ ↑
(c) 2Al + 2H₂SO₄ → Al₂O₃ + SO₂ + SO₃ + 2H₂ ↑