Science In Everyday Life Solutions for Class 8 Science Chapter 4 Metals And Non Metals are provided here with simple step-by-step explanations. These solutions for Metals And Non Metals are extremely popular among Class 8 students for Science Metals And Non Metals Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Science In Everyday Life Book of Class 8 Science Chapter 4 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Science In Everyday Life Solutions. All Science In Everyday Life Solutions for class Class 8 Science are prepared by experts and are 100% accurate.

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Question 1:

Which property of metals makes them suitable for use in jewellery?

Answer:

Metals has a unique property that they can be drawn into thin sheets. This property is called as malleability. Since, gold and silver are most malleable metals, this property makes them suitable for jewellery. Their lustre adds to the beauty of jewellery.

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Question 2:

Why are metals used for making electrical cables?

Answer:

Metals can be drawn into thin wires because of their ductile property. Also metals are good conductors of electricity. Therefore, metals are used for making electrical cables.

Page No 67:

Question 1:

Write one word for the following.

1. Non-metal with metallic lustre ....................
2. A non-metal that is the hardest substance known ....................
3. Metal that can be cut with a knife ....................
4. Non-metal that is a good conductor of electricity ....................
5. Metal that is stored in kerosene ....................

Answer:

1. Iodine
2. Diamond
3. Sodium
4. Graphite
5. Sodium

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Question 2:

Define the following.
1. Malleability
2. Ductility
3. Sonority
4. Corrosion

Answer:

1. The property of metals, which makes the metals to be drawn into thin sheets is called malleability.

2. The property of metals, which makes the metals to be drawn into thin wires is called ductility.

3. Sonority is the property of a metal which produces ringing sound when struck by a hard object.

4. When a metal is continuously exposed to atmospheric gases and moisture, the surface of the metals get slowly corroded or eaten away. This is called as corrosion.

Page No 67:

Question 1:

Non-metal that is liquid at room temperature is
(a) chlorine
(b) bromine
(c) oxygen
(d) iodine

Answer:

(b) bromine.
Bromine is a non-metal that is liquid at room temperature.

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Question 2:

Sonority is the ability to
(a) break
(b) produce a ringing sound when struck with a hard object
(c) be beaten into thin sheets
(d) be drawn into wires

Answer:

(b) Produce a ringing sound when struck with a hard object
Sonority is the ability to produce a ringing sound when struck with a hard object.

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Question 3:

Which of the following is not a characteristic of a metal?
(a) Shine brightly when polished
(b) Bad conductors of electricity and heat
(c) Generally solid at room temperatures
(d) Can be drawn in to thin wires

Answer:

(b) Bad conductors of electricity and heat.
Metals are generally good conductors of heat and electricity.

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Question 4:

The products formed when zinc reacts with sulphuric acid
(a) zinc chloride and hydrogen
(b) zinc sulphate and water
(c) zinc sulphate and hydrogen
(d) zinc nitrate and hydrogen

Answer:

(c) Zinc sulphate and hydrogen
Zinc sulphate and hydrogen are formed when zinc reacts with sulphuric acid.

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Question 5:

The order of reactivity of metals is
(a) K > Na > Ca > Au
(b) K > Ca > Na > Mg
(c) Fe > Na > Mg > Au
(d) Cu > Fe > K > Na

Answer:

(a) K > Na > Ca > Au
The order of reactivity of metals depend upon the position of the metals in the activity series. In the given options, the correct order of reactivity of metals is K > Na > Ca > Au.

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Question 1:

Fill in the blanks with the correct words.
1. The property by virtue of which metals can be beaten into thin sheets is called .................... (malleability/ductility).
2. .................... (Copper/Silver) is the best conductor of heat.
3. .................... (Graphite/Iodine) is a good conductor of electricity.
4. Non-metallic oxides dissolve in water to form .................... (acids/bases).
5. .................... (Zinc/Silver) will displace copper from copper sulphate solution.

Answer:

1. The property by virtue of which metals can be beaten into thin sheets is called malleability.
2. Silver is the best conductor of heat.
3. Graphite is a good conductor of electricity.
4. Non-metallic oxides dissolve in water to form acids.
5. Zinc will displace copper from copper sulphate solution.



Page No 68:

Question 3:

Why is rusting of iron an undesirable change?

Answer:

When iron comes in contact with oxygen and moisture in the atmosphere it forms a reddish brown substance on its surface called rust. In due course of time, the flakes of rust falls of from the surface, exposing the surface of the iron for further rusting. This makes the iron weak. Thus, rusting is an undesirable change.

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Question 4:

Why do copper vessels turn green with the passage of time?

Answer:

When copper comes in contact with carbon dioxide and moisture in the atmosphere it forms copper carbonate. In course of time, due to continuous exposure to carbon dioxide and moisture, copper gets a coating of this green substance on its surface called copper carbonate.

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Question 5:

Why do silver objects turn black on exposure to air?

Answer:

Silver reacts with hydrogen sulphide gas present in the atmosphere forming silver sulphide. This blackens the silver objects and they lose their shine with the passage of time.

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Question 6:

Write one use each of any two metals and non-metals.

Answer:

Uses of metals:
(i) Metals like gold and silver are used in jewellery making because of their malleable property.
(ii) Metals like copper and silver are used in the manufacture of cooking utensils because of their thermal conductivity.

Uses of non metals;
(i) Hydrogen is used in welding torches.
(ii) Phosphorous is used for making special glasses used in sodium lamps.

Page No 68:

Question 1:

Compare the following properties of metals and non-metals: ductility, thermal conductivity, and electrical conductivity.

Answer:

Property  Metals  Non-metals
Ductility Metals like gold, silver, copper etc. can be drawn into thin wires. This property of metals is called ductility. Non-metals are brittle and hence does not possess ductility.
Thermal conductivity Metals are very good conductors of heat.Thus,metals like silver and copper are used in making cooking utensils. Non-metals, except diamond, are bad conductors of heat. Therefore, they are used in making handles for cookware sets.
Electrical conductivity Metals are very good conductors of electricity and therefore, are used in making of electrical wires and cables. Non-metals, except graphite, are bad conductors of electricity and therefore, are used in preparing insulating materials.

Page No 68:

Question 2:

Write word equations and chemical equations for the following:
(a) reaction of zinc with sulphuric acid
(b) reaction of magnesium with sulphuric acid
(c) reaction of aluminium with hydrochloric acid

Answer:

(a) When sulphuric acid is added to zinc, zinc reacts with sulphuric acid forming zinc sulphate, liberating hydrogen gas.
       
        Zn + H2SO4 Z nSO4 + H2
      

(b) When sulphuric acid is added to magnesium, magnesium reacts with sulphuric acid forming magnesium sulphate, liberating hydrogen gas.

       Mg+H2SO4  MgSO4+H2
       
(c) When hydrochloric acid is added to aluminium, aluminium reacts with hydrochloric acid forming aluminium chloride, liberating hydrogen gas.
       
        2Al + 6HCl 2 AlCl3 + 3H2
      
        

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Question 3:

What is a displacement reaction? Explain the statement 'Iron can displace copper from its salt solution but copper cannot displace iron from its salt solution.'

Answer:

A displacement reaction is a reaction during which a metal reacts with salt solution and displaces the metal present in it.
To explain the displacement reaction of metals, a list of common metals are arranged in decreasing order of their reactivity which is called as active series of metals. The metals which are placed higher in the activity series will have a high reactivity which reduces as we go down the series. Iron can displace copper from its salt solution but copper cannot displace iron from its salt solution because iron is placed higher in activity series from copper.

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Question 4:

On the basis of the activity series of metals, predict how these metals will react with each of the following salt solutions:
Metals: magnesium, zinc, copper, iron, and potassium
Salt solutions: magnesium sulphate, zinc sulphate, copper sulphate, iron sulphate, and potassium sulphate

Answer:

   Magnesium Sulphate  Zinc Sulphate  Copper Sulphate  Iron Sulphate  Potassium Sulphate
Magnesium No reaction Forms magnesium sulphate and zinc Forms magnesium sulphate and copper Forms magnesium sulphate and iron No reaction.
Zinc No reaction  No reaction Forms zinc sulphate and copper Forms zinc sulphate and iron No reaction
Copper No reaction No reaction No reaction No reaction No reaction
Iron No reaction No reaction Forms iron sulphate and copper No reaction No reaction
Potassium Forms potassium sulphate and magnesium Forms potassium sulphate and zinc Forms potassium sulphate and copper Forms potassium sulphate and iron No reaction



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