Class 8 Science Lesson 4 Inside Question and Answer NCERT & CBSE Board Here in this post. NCERT Class 8 Science Textbook Lesson 4 Inside Questions.
Lesson 4 Materials : Metals And Non-Metals.
Que. 1) fill in the blanks .
(1) The properties of metal by which it can be drawn into wires is called—–
(2) Non –metals are —- conductors of heat and —–
Ans- bad , electricity.
(3) The sulphrous acid turns —- litmus paper into —-
Ans- blue , red
Que. 2) answer the following questions.
(1) Define malleability .
Ans- The property of metals by which they can be beaten into thin sheets is called Malleability.
(2) Define ductility.
Ans- the property of metal by which it can be drawn into wires is called ductility.
(3) Give difference between metals and non – metals.
Metals are the good conductor of electricity.
|Non-metals are bad conductor of electricity.|
|Metals are malleable, ductile ,sonorous and good conductors of heat.||
Non- metals are non malleable, non ductile and bad conductors of heat.
For example- aluminium, copper, calcium, magnesium etc
For example-carbon, oxygen, phosphorous etc.
(4) Explain displacement reaction with example.
Ans- the displacement of metals of one reaction to another reaction are called as displacement reaction. In the displacement reaction more reactive metal can replace by less reactive metal ,but a less reactive one cannot replace by more reactive one. For example- CuSO4 + Zn – ZnSO4 + Cu in this reaction zinc is more reactive than copper iron so it replaces the copper iron.
(5) Give uses of metals and non-metals.
Ans- there are various uses of metals and non- metals in our daily life. Metals are used in making machinery , automobailes, aeroplanes, trains, satellites, industrial gadgets, cooking utensils, water boilers etc. similarly non- metals are also used in fertilizers to enhance the growth of plants, non-metals are also used in water purification process, they are also used in purple cloured solution which is applied on wounds as an antiseptic , non-metals are also used in crackers. Etc are the different uses of metals and non- metals.
(6) Why sodium is stored in kerosene.
Ans- sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction therefore it is stored in kerosene.
(7) Phosphorous stored in water, why?
Ans- generally non-metals are stored in water. Phosphorous is a non –metals. It is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorous with atomospheric oxygen it is stored in water.