science class 8 chapter 4 question answer and exercise
Answers
Access Answers to NCERT Class 8 Science Chapter 4 Materials – Metals and Non-Metals
Exercise Questions
1. Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Soln:
Answer is a) Zinc
Explanation:
Here, Zinc is a metal with malleability and ductility whereas Phosphorus, Sulphur and Oxygen are nonmetals which lack malleability and ductility.
2. Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Soln:
Answer is (c) Generally, metals are ductile.
Explanation:
Ductility is a property where a substance can be drawn into thin wires, Generally, metals are ductile with mercury as the exception.
3. Fill in the blanks.
(a) Phosphorus is a very _________non-metal.
(b) Metals are _________ conductors of heat and ____________ .
(c) Iron is ____________reactive than copper.
(d) Metals react with acids to produce ____________ gas.
Soln:
(a) Phosphorus is a very reactive non-metal.
(b) Metals are good conductors of heat and electricity.
(c) Iron is more reactive than copper.
(d) Metals react with acids to produce hydrogen gas.
4. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids. ( )
(b) Sodium is a very reactive metal. ( )
(c) Copper displaces zinc from zinc sulphate solution. ( )
(d) Coal can be drawn into wires. ( )
Soln:
a) False
b) True
c) False
d) False
5. Some properties are listed in the following table. Distinguish between metals and non-metals on the basis of these properties.
Properties Metals Non-metals
1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of Electricity
Soln:
Properties Metals Non-metals
1. Appearance Lustrous Dull
2. Hardness Hard Soft
3. Malleability Have property of Malleability Do not have a property of Malleability
4. Ductility Have property of Ductility Do not have the property of Ductility
5. Heat Conduction Good conductor of Heat Bad Conductor of Heat
6. Conduction of Electricity Good conductor of Electricity The bad conductor of Electricity