NCERT Exemplar Solution Class 8 Science Chapter 4
NCERT Exemplar Solution Class 8 Science Chapter 4 Materials: Metals and Non-Metals all Questions Answer Solution. NCERT Exemplar Class 8 Science Chapter 4 Solution PDF.
NCERT Exemplar Solution Class 8 Science Chapter 4: Overview
NCERT Exemplar Solution Class 8 Science Chapter 4 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
8 |
Subject |
Science |
Chapter |
4 |
Chapter Name |
Materials: Metals and Non-Metals |
NCERT Exemplar Solution Class 8 Science Chapter 4 Materials: Metals and Non-Metals
Multiple Choice Questions
1) Which of the following is not a metal?
a) Copper
b) Sulphur
c) Aluminum
d) Iron
Answer:- b) Sulphur
Sulphur is a non-metal. Copper, iron , and aluminum are metals.
2) The substance that will be flattened on Beating with a hammer is
a) Crystal of iodine
b) Lump of sulphur
c) Piece of coal
d) Zinc granule
Answer:- d) zinc granule
Zinc granule are malleable as it is a metal. Therefore on Beating with hammer it gets flattened. Sulphur, coal and iodine does not have these property, they are non metal.
3) Boojho has learnt that non- metals on Beating with a hammer are generally broken into pieces. Which of the following is a non- metal?
a) Iron nail
b) Aluminum wire
c) Copper plate
d) Piece of coal
Answer:- d) piece of coal
Coal is non metal. It does not have the property of malleability. Therefore it broken into pieces. Iron, aluminium and copper are metals.
4) Materials which can be drawn into wires are called ductile. Which of the following is not a ductile material?
a) Silver
b) Copper
c) Sulphur
d) Aluminum
Answer:- c) Sulphur
Sulphur is non metal it does not possess the property of ductility. Silver, copper and aluminum are metals.
5) Metals are generally hard. Which of the following metals is an exception and can be cut with a knife?
a) Iron
b) Sodium
c) Gold
d) Magnesium
Answer:- b) Sodium
Iron, gold and magnesium cannot be cut with knife. But two exception are there which are sodium and potassium. These are metals but soft metals. These can be cut with knife.
6) Metals are generally solid. Which of the following metals is in liquid state at room temperature?
a) Mercury
b) Silver
c) Aluminum
d) Sodium
Answer:- a) Mercury
Mercury is an exception. it is only metal which is present in the liquid state at room temperature.
7) Metals generally react with dilute acids to produce hydrogen gas. Which one of the following metals does not react with dilute hydrochloric acid?
a) Magnesium
b) Aluminum
c) Iron
d) Copper
Answer:- d) Copper
Copper does not react with the dilute hydrochloric acid. But it reacts with sulphuric acid.
8) Which of the following reacts with cold water vigorously?
a) Carbon
b) Sodium
c) Magnesium
d) Sulphur
Answer:- b) Sodium
Sodium is very reactive metal. It reacts vigorously with water and oxygen gas. Therefore it is stored in kerosene.
9) The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is
a) Copper
b) Iron
c) Aluminium
d) Sodium
Answer:- c) Aluminium
Aluminium on reaction with hydrochloric acid and sodium hydroxide gives hydrogen gas. Copper , iron and sodium does not produce it.
10) Which of the following non – metals reacts and catches fire on exposure to air?
a) Phosphorus
b) Nitrogen
c) Sulphur
d) Hydrogen
Answer:- a) Phosphorus
Nitrogen and hydrogen is already present in air. Sulphur does not catches fire on exposure to air. Phosphorus reacts with air and catches fire.
11) Generally metallic oxides are basic and non- metallic oxides are Acidic in nature. Solution of which of the following oxides in water will change the colour of blue litmus to red?
a) Sulphur dioxide
b) Magnesium oxide
c) Iron oxide
d) Copper oxide
Answer:- a) Sulphur dioxide
Oxides of non- metals are acidic in nature and therefore Sulphurous acid will change blue litmus paper red.
12) Which of the following property is not responsible for copper to be used as electrical conduction wires?
a) Ductility
b) Colour
c) Good conductor of electricity
d) It is solid
Answer:- b) Colour
Colour is not responsible for using copper wire as electrical conduction wires.
Ductility, solid and good Conductor of Electricity are important for conduction wires.
Very Short Answer Questions
13) Name two soft metals which can be cut with a knife.
Answer:- the two metals Sodium and potassium are soft metals and these can be cut easily with a knife.
14) Which non- metal is essential for our life and all living beings inhale it during breathing?
Answer:- Oxygen is a non- metal which is important gas for all living beings. Oxygen is inhaled during breathing, and it is essential for life.
15) Name two major non- metals which are present in fertilizers and enhance the growth of plants.
Answer:- nitrogen and Phosphorus are very much important for the growth of plant. It is present in Fertilizerswhich makes the plant to grow faster.
16) Which non- metal is used to disinfect water ?
Answer:- Chlorine Is a non-metal which is used to disinfect the water. Chlorination is the commonly used method for the disinfecting and purifying water. Chlorine tablets or bleaching powder is used in this process.
17) A purple coloured non- metal forms a brown solution in alcohol which is applied on wounds as an antiseptic. Name the Non- metal.
Answer:- iodine is a non-metal which used as an antiseptic. It is purple in colour and forms solution in alcohol and applied on wounds.
18) Zinc sulphate forms a colourless solution in water. Will you observe any colour on adding copper turning in it?
Answer:- Zinc sulphate forms a colourless solution in water, if we add copper turning in it then also the zinc sulphate solution will not change any colour as the displacement reaction does not takes place in it.
19) Why are bells made of metals ?
Answer:- Metals can produce ringing sounds, these property of metal is known as sonorous. Bells are produced to make ringing sounds and the metals are used to make it. Also metals are hard so that the bells does not get affected during production of sound.
20) Which liquid Metal is used for making Thermometers?
Answer:- mercury is a metal which is present in the liquid state at Normal room temperature . This liquid metal is used for making Thermometers . Mercury expand on increasing temperature and thus shows the correct temperature in thermometer.
21) Which of the following metal can displace the other two metals from their salt solutions?
Zinc, iron, copper
Answer:- Zinc
Zinc can replace both Iron and copper from their salt solutions. The reaction is known as displacement reaction. Zinc is more reactive as compared to iron and copper. A more reactive metal will replace the less reactive metal, but less reactive will not replace the more reactive metal. And therefore zinc will displace both metals.
Short Answer Questions
22) Paheli bought a statue made of copper. To her surprise it acquired a dull green coating after a couple of months. Explain the reason.
Answer:-
When a copper utensils or vessels is comes in contact with the moist air for longer time then a greenish coating takes place over it. These green coating is mainly mixture of copper hydroxide and copper carbonate. Moist air contains water molecules, oxygen gas and carbon dioxide gas which reacts with the copper and forms the green voat over it.
23) In fig. 4.1 you find that the bulb glows when an iron nail is placed between two ends of wire. Complete the following sentences on the bases of this fact.
Fig. 4.1
a) ______________ is a metal.
Answer:- iron is a metal.
b) Metals are good __________ of electricity.
Answer:- Metals are good Conductor of electricity.
24) If in fig. 4.1 iron nail is replaced by a wooden stick, will the bulb glow or not? Justify your answer.
Answer:-
No. The bulb will not glow If we replaced the iron nail with the wooden stick . Because wood is bad Conductor of electricity. Therefore it will not carry current in it and thus bulb will not glow.
25) Paheli prepared a blue coloured solution of copper sulphate in beaker A and placed an iron nail in it. Boojho prepared a yellowish green solution of ferrous sulphate in beaker B and placed a copper wire in it. What changes will they observe in the two beakers after an hour?
Answer:- After one hour we will observe that –
The solution in the breaker A will change its colour from blue to yellowish green And the brown layer of copper will be deposited on the iron nail kept in solution. In the beaker B there will not be any change after one hour.
26) A doctor prescribed a tablet to a patient suffering from iron deficiency. The tablet does not look like iron. Explain.
Answer:- Doctor prescribed the tablets to The patient suffering from an iron deficiency but these tablets are not made up of iron nails. These tablets are made up of salts of iron.
27) Match the substances in Column A with their applications given in Column B.
Column A
(Substances |
Column B
(Application) |
a) Oxygen | i) For making crackers |
b) Copper | ii) for disinfecting water |
c) Sulphur | iii) all living beings inhale during breathing |
d) Iron | iv) for making electric wires |
e) Chlorine | v) for making rails |
Answer:-
a) Oxygen → iii) All living being inhale
During breathing
b) Copper → iv) for making Electric wires
c) Sulphur → i) for making crackers
d) Iron → v) for making rails
e) Chlorine → ii) For disinfecting water
Long Answer Questions
28) Some of the following statements are incorrect. Find the incorrect statements and correct them.
a) The property of metals by virtue of which they can be drawn into wires is called ductility.
Answer:- Correct
b) Metals are good conductor of electricity but poor conductor of heat.
Answer:- Incorrect
Metals are good Conductors of both heat and electricity.
c) Articles made of metals produce ringing sound when struck hard.
Answer:- correct
d) Oxides of non- metals and metals are acidic in nature.
Answer:- Incorrect
Oxides of non- metals are Acidic in nature but oxides of metals are not Acidic in nature it is basic in nature.
e) A less reactive metal replace a more reactive metal from its salt solution in water.
Answer:- Incorrect
A less reactive metal does not replace a more reactive metal from its salt solution in water, but more reactive metal replace the less reactive metal from its salt solution in water.
29) Iron is more reactive than copper. Can you write an activity to show this?
Answer:-
Take two beakers A and B.
Take solution of copper sulphate and iron nail in beaker A.
And take solution of iron sulphate and copper turnings in beaker B.
Now keep the beakers untouched for some time, and observe the change in it.
We will observe that
The colour in beaker A is changed from blue to yellowish green. And there is deposition of brown layer on iron nail.
These indicates that the iron has displace the copper in solution.
But In beaker B there is no any change. These is because
Only a more reactive metal displace the less reactive metal in its aqueous solution. But less reactive metal does not replace the more reactive metal.
These activity proves that the iron is more reactive than copper.
30) Fill in the blanks to complete the following paragraph.
The name of the product formed in the reaction of sulphur and ______________ is sulphur dioxide gas. When sulphur dioxide is dissolved in ________, sulphurous acid is formed. The Sulphurous acid turns ____________ litmus paper to __________. generally oxides of _________ are acidic in nature.
After completing the paragraph write two questions which you can raise on the basis of this information.
Answer:-
The name of the product formed in the reaction of sulphur and oxygen is sulphur dioxide gas. When sulphur dioxide is dissolved in water, Sulphurous acid is formed. The Sulphurous acid turns blue litmus paper to red . generally oxides of non- metals are Acidic in nature.
31) Find out the names of three metals and three non- metals from the box given as fig. 4.2.
Fig. 4.2
Answer:-
Metals :- iron, copper, Aluminium
Non- metals:- carbon , oxygen, sulphur.
32) Complete the crossword given in fig. 4.3 with the help of the clues.
Fig. 4.3
Across-
1) Which is generally hard, ductile, malleable and sonorous.
2) A metal is called so it can be drawn into wires.
3) Metal bells are used because of this property.
Down-
4) A metal generally used for making jewellery.
5) A metal which is liquid at room temperature.
6) A metal which reacts with acid as well as base to form hydrogen gas.
7) Substances used to enhance the growth of plants.
8) Property by virtue of which metals can be beaten into thin sheets.
Answer:-