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NCERT Solution for Class 10 Science Chapter 3 : Metals and Non-Metals

Metals and Non-Metals
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Chapter 3 of Class 10 Science is Metals and Non-Metals. In this chapter, you will study about the physical and chemical properties of different metals and non-metals. It makes you understand the occurrence of metals in the environment and its extraction as well as the process of corrosion of metals. There are overall 16 questions in this chapter. This detailed solution provided by Swiflearn will strengthen your concepts.

NCERT Solutions for Class 10 Science Chapter 3 by Swiflearn are by far the best and most reliable NCERT Solutions that you can find on the internet. These NCERT Solutions for Class 10 Science Chapter 3 are designed as per the CBSE Class 10th Science Syllabus. These NCERT Solutions will surely make your learning convenient & fun. Students can also Download FREE PDF of NCERT Solutions Class 10 Science Chapter 3.

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NCERT Solution for Class 10 Science Chapter 3 Metals and Non-Metals

Exercise 3.1

Question 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? 

Solution:
i. Metal which exists as liquid at room temperature → Mercury
ii .Metal which can be easily cut with a knife → Potassium
iii. Metal which is the best conductor of heat → Copper and silver
iv. Metals which are poor conductors of heat → Mercury

Question 2:
Explain the meanings of malleable and ductile.

Solution:
Malleable: Metals can be beaten, hammered or pressed into thin sheets or other shapes without breaking or cracking due to the elastic nature of metals are called malleable. For example, most of the metals are malleable except zinc.
Ductile: Metals can be drawn into thin wires or chains i.e. that are able to deform without losing toughness due to the elastic nature of metals are called ductile. For example, most of the metals are ductile except zinc

Exercise: 3.2

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

Solution 1:
(i) Mineral: The mineral which are present as mixture of metallic compounds and extractable impurities are known as ores and the compound of a metal found in nature is called mineral.
(ii) Ore: The natural occurring solid materials or minerals from which the metals can be conveniently and economically extracted are known as ores.
(iii) Gangue: The ore contains some impurities like sand, clay and rocky material. These impurities are called gangue or matrix. Gangue is removed before the metallurgical process starts.

Question 2:
Write equations for the reactions of:
(i) iron with steam
(ii) calcium and potassium with water

Solution 2:
(i) 3Fe(s) + 4H2O (g)→Fe3O4 (aq) +4H2 (g)
(Iron) (Steam) (Iron (II, III) oxide) (Hydrogen)
(ii) Ca + 2H2O → Ca(OH)2 + H2 + Heat
2K + 2H2O → 2KOH + H2 + Heat

Question 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 above given table to answer the below 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 the solution of copper (II)
sulphate?
(iii) Arrange the metals A, B, C and D in the order of their decreasing
reactivity.

Solution 3:
According to the activity series the most reactive metal displaces the least reactive metal according to the given table we can say that:
A is less reactive than iron (Fe) but more reactive with copper (Cu).
A + FeSO4 → No reaction
A + CuSO4 → Single Displacement
B is more reactive than iron (Fe) but less reactive than zinc (Zn).
B + FeSO4 → Single Displacement
B + ZnSO4 → No reaction
C is less reactive than iron (Fe), copper (Cu) and zinc (Zn) but more reactive with silver (Ag).
C + FeSO4 → No reaction
C + CuSO4 → No reaction
C + ZnSO4 → No reaction
C + AgNO3 → Single Displacement
D is less reactive than iron (Fe), copper (Cu),zinc (Zn), and silver (Ag).
D + FeSO4 → No reaction
D + CuSO4 → No reaction
D + ZnSO4 → No reaction
D + AgNO3 → No Reaction
(i) B is the most reactive metal.
B + FeSO4 → Single Displacement
(ii) When B is added to a solution of copper (II) sulphate then it shows the single
displacement because B is more reactive than iron.
B + CuSO4 →Single Displacement
(iii) The order of decreasing reactivity of the given metals are: B > A > C > D

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

Solution 4:
According to the activity series, iron is more reactive than hydrogen so it can displace the hydrogen. When iron reacts with sulphuric acid it evolves the hydrogen gas.
Fe(s) + H2SO4 (aq) → FeSO4 (aq) + H2 (g)

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

Solution 5:
According to the activity series, zinc is more reactive than iron so it can displace the iron from its salt solution. Iron sulphate is green in colour, its changes into brown.
Zn(s) + FeSO4 (aq) → ZnSO4 (aq) + Fe(s)

Exercise: 3.3
Question .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?

Solution:
When the valence electrons are represented as dots circling the elements, it is known as the elemental structure with electron dot structure of that element.
(i) Electron Dot Structure:
• Sodium (2, 8, 1) = one electron at the top of Na.
• Oxygen (2, 6) = O two electrons each on three sides of O.
• Magnesium (2, 8, 2) = two electrons on the top of Mg.
(ii) The formation of Na O and MgO can be writ 2 2 ten as Mg 2+ + O 2- ( ) ( )

Question 2:
Why do ionic compounds have high melting points?

Solution 2:
Ionic compounds have high boiling and melting points due to strong electrostatic force of attraction between the oppositely charged ions, and hence a large amount of energy is then required to break that strong bonding force between those ions.
The constituent ions have rigid packing which results in high melting and boiling points.

Exercise: 3.4

Question 1:
Define the following terms:
(i) mineral
(ii) ore
(iii) gangue

Solution 1:
(i) Mineral: The mineral which are present as mixture of metallic compounds and
extractable impurities are known as ores and the compound of a metal found in nature is called mineral.
(ii) Ore: The natural occurring solid materials or minerals from which the metals can be economically and conveniently extracted are known as ores.
(iii) Gangue: The ore contains some impurities like sand, clay and rocky material. These impurities are called gangue or matrix. Gangue is removed before the metallurgical process starts.

Question 2:
Name two metals which are found in nature in their Free State.

Solution 2:
The least reactive metals are found in nature in the Free State. For example: Silver (Ag),  Gold (Au), and Platinum (Pt). Since they are least reactive so they are found in Free State.

Question 3:
Which chemical process is used in order to obtain a metal from its oxide?

Solution 3:
Electrolysis process is used to reduce the highly reactive metals, while Moderate reactive metals can be reduced by either carbon or carbon monoxide.
Suitable reducing agents such as carbon or highly reactive metals are used to reduce the metal oxides, by displacing the metals from their oxides.
For example, zinc oxide can be reduced to metallic zinc (Zn) by either heating with carbon or CO, as discussed above.
ZnO + C → Zn + CO
Or
ZnO + CO + → + Zn +CO2
Thermite process: It is a process of extracting metal by reducing its oxide by treating it with aluminium powder. It is also called as Goldschmidt process and it is an exothermic reaction. Chromium oxides are reduced to chromium:
Cr2O3 + 2Al →Al2O3 +2Cr + heat

Exercise: 3.5

Question 1:
Metallic oxides of zinc (Zn), magnesium (Mg) and copper (Cu) were heated
with the following metals given below:
In which cases you will find displacement reactions taking place?

Solution 1:
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

Question 2:
Which metals do not corrode easily?

Solution 2:
The slow eating up of metals by the action of air, moisture or a chemical on their surface is called corrosion. Most reactive metals corrode readily due to the action of moisture and air. Hence, less reactive metals are less likely to get corroded.

Question 3:
What are alloys?

Solution 3:
An alloys is a homogenous mixture of two or more metals or a metal and non-metal. Alloys are formed by mixing two or more metals by melting them and cooling them finally. On cooling, the mixture solidifies and is called an alloy. The constituents are mixed
homogenously. For example,
• Bronze: Copper + Tin
• Brass: Copper + Zinc
• Nichrome: Nickel + Chromium.
• Electrum: Gold + Silver.

Exercise Chapter 3

Question 1:
Which of the following given pairs will give the 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.

Solution 1:
(d) AgNO3 solution and copper metal

Question 2:
Which of the given following methods is preferably 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.

Solution 2:
(c) Applying a coating of zinc

Question 3:
An element X reacts with oxygen to give a compound with a high melting
point. That compound is also soluble in water. The element X is likely to
be:
(a) Calcium
(b) Carbon
(c) Silicon
(d) Iron

Solution 3:
(a) The element is likely to be calcium.

Question 4:
Food cans are generally coated with tin and not with zinc, why?
(a) Zinc is costlier than tin.
(b) Zinc has higher melting point than tin.
(c) Zinc is more reactive than tin.
(d) Zinc is less reactive than tin.

Solution 4:
(b) Zinc is more reactive than tin.

Question 5:
You are provided with a hammer, a battery, a bulb, wires and a switch:
a) How could you use them to clearly distinguish between the samples of
metals and non-metals?
b) Assess the usefulness of these tests in distinguishing between metals andNnon-metals.

Solution 5:
a) Metals are malleable in nature. With the help of hammer, we can beat the given sample. If its converts into its thin sheets, then that sample is metal otherwise nonmetal. When we will use the battery, a bulb, wires and a switch to set up a circuit, then metals conduct electricity. If the circuit completes and bulb glows then it will represent the metallic
nature of the sample due to free electrons. If the bulb will not glow, then it will represent the non-metallic nature of the given sample.
b) These test represents the physical properties like malleability and ductility of the metals and non- metals. Thus we can differentiate easily between them with the help of their physical properties.

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

Solution 6:
Amphoteric oxides are those oxides which can reacts with acid as well as base. Examples:
Zinc oxide (ZnO) and Aluminium oxide (Al2O3).

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

Solution 7:
More reactive metals will displace hydrogen from its dilute acids. For example: Iron and Zinc.
Fe + 2HCl → FeCl2 + H2
Zn + 2HCl → ZnCl2 + H2
Least reactive metals will not displace hydrogen from its dilute acids. For example: copper and silver
Cu + HCl → No Reaction
Ag + HCl → No Reaction

Question 8:
In the electrolytic refining process of any metal M, what would you choose
for the anode, the cathode and the electrolyte?

Solution 8:
In the electrolytic refining of a metal M:
Cathode → pure metal M
Anode → impure metal M
Electrolyte → Salt Solution of the metal M

Question 9:
Pratyush took Sulphur powder on a spatula and heated it for a while. He
then collected the gas evolved due to heating, by inverting a test tube over
it, as shown below:
a) What will be the action or effect of gas evolved on:
(i) Dry litmus paper?
(ii) Moist litmus paper?
b) Also write a balanced chemical equation for the reaction taking place.

Solution 9:
(a)
(i) No action on dry litmus paper.
(ii) Moist blue litmus turns to red due to the formation of sulphur dioxide. sulphur dioxide is acidic oxide when it will react with water converts into sulphurous acid.
(b) S + O2 → SO2
SO2 + H2O → H2SO3

Question 10:
State two ways for preventing the rusting of an iron

Solution 10:
Rusting is defined as a process where the substance will degrade usually metals. Metal converts into its hydrated oxides. Ex: Fe,Cu, Ag
The two ways from preventing the rusting of iron are:
(i) Painting, Oiling: Iron articles gets corrode easily in the presence of moisture and air. For the prevention of rusting, we have to paint the iron articles. When we apply the paint on iron articles the supply of moisture and air will stop.
(ii) Galvanization: It is a process of applying a protecting coating of zinc metal, which prevents the iron or steel to come in contact with moisture and oxygen, hence it prevents from rusting.

Question 11:
What oxides are formed when the non-metals combine with oxygen?

Solution 11:
Non-metals reacts with oxygen to form acidic oxides. These oxides further reacts with water to form acids. For example: S + O2 → SO2

Question 12:
Give reasons
(a) Why platinum, gold and silver are used to make jewellery.
(b) Why sodium (Na), potassium (K) and lithium (Li) are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for
cooking, why?
(d) Carbonate and sulphide ores are usually converted into oxides during
the process of extraction.

Solution 12:
(a) Platinum, gold and silver are used to make jewellery because they are least reactive metals and do not corrode easily. They are lustrous.

(b) Sodium, potassium and lithium are stored under oil because they are very reactive metals and vigorously react with air as well as water with lots of energy. Therefore, they are kept immersed in kerosene oil.

(c) Aluminium in spite of being highly reactive metal, is used to make utensils for cooking because it resist to corrosion and is a good conductor of heat. Aluminium reacts with oxygen present in air to form a thin white layer of aluminium oxide (Al2O3). This oxide layer prevents further reaction of aluminium due to stability of this oxide.

(d) Carbonate and sulphide ores are generally converted into oxides because metals can be easily extracted from their oxides, by using the calcinations and roasting process, rather than from their carbonates and sulphides.

Question 13:
You must have seen in your home that tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are used and are effective in cleaning the vessels?

Solution 13:
Copper reacts with moist carbon dioxide in air to form basic copper carbonate (CuCO3. Cu(OH)2). It is green in colour and copper vessel loses its shiny brown surface. When we apply the lemon or tamarind neutralizes the basic copper carbonate due to the presence of citric acid and dissolves the layer.

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

Solution 14:  Refer pdf.

Question 15:
A man went door to door pretending to be a goldsmith. He promised that
he can bring back the glitter of old and dull gold ornaments. An
unsuspecting lady gave him a set of gold bangles, which he dipped in a
specific solution. After dipping, the bangles sparkled like new but their
weight was reduced drastically. The lady became upset but after a pointless
argument the man beat a hasty retreat. Can you play the role of a detective
to find out the nature of that solution which he used?

Solution 15:
According to the activity series, gold is least reactive metal. It will not react with any acid or base. When we keep the gold in aqua regain than gold dissolve in it. The outer layer of gold gets dissolved, so the weight of ornaments reduced and inner layer appears. Aqua regain is a mixture of 3 parts of HCl and 1 parts of HNO3.

Question 16:
Give reasons that why copper (cu) is used to make hot water tanks but not
steels (an alloy of iron)?

Solution 16:
According to the activity series, copper is least reactive than hydrogen, it will not displace hydrogen. However, iron reacts with steam. If the hot water tanks are made of steel then iron would react vigorously with the steam and will corrode easily.
3Fe + 4H2O → Fe3O4 + 4H2

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