Class 8 Combustion And Flame CBSE Questions & Answers

Class 8 · Combustion And Flame

This is Science Class 8 Combustion and Flame CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Ignition temperature of which of the following will be highest ?
  • A
    petrol
  • B
    phosphorus
  • C
    dry paper cup
  • D
    wet paper cup
    Correct
2
Combustion of coal releases particulate matter that may lead to :
  • A
    goitre
  • B
    arthritis
  • C
    bone cancer
  • D
    asthma
    Correct
3
The innermost zone of flame is least hot due to :
  • A
    presence of melting wax
  • B
    absence of oxygen
  • C
    presence of unburnt carbon particles
    Correct
  • D
    absence of unburnt carbon particles
4
If we want to fight fire we should do :-
  • A
    we should cool down combustible substance below ignition temperature
  • B
    we should remove combustible substance
  • C
    all the these
    Correct
  • D
    we should cut off the supply of oxygen
5
Read the following statements :i) Combustion of most fuels is believed to cause global warming.ii) All the available fuels are ideal fuels.
  • A
    both are correct
  • B
    statement ii) is correct but i) is wrong
  • C
    statement i) is correct but ii) is wrong
    Correct
  • D
    both are wrong
6
A substance that has relatively low ignition temperature exhibits :
  • A
    rapid combustion
  • B
    slow combustion
  • C
    spontaneous combustion
    Correct
  • D
    incomplete oxidation
7
To put out a fire :
  • A
    air should be removed
  • B
    heat should be removed
  • C
    either of following should be removed
    Correct
  • D
    fuel should be removed
8
A paper cup containing water in it doesn
  • A
    paper cup loses heat by induction
  • B
    paper cup loses heat by conduction
    Correct
  • C
    paper cup is made of non metal
  • D
    paper cup loses heat by combustion
9
A carbon dioxide fire extinguisher cylinder is filled with :
  • A
    solid carbon dioxide
  • B
    gaseous carbon dioxide
  • C
    liquid carbon dioxide
    Correct
  • D
    gel based carbon dioxide
10
During incomplete combustion, fuel gives out :
  • A
    oxygenated flame
  • B
    yellow flame
    Correct
  • C
    black flame
  • D
    blue flame
11
Read the following statements :i) Substances having high ignition temperature take more time to burn while substance having low ignition temperature takes less time to burn.ii) Substances having low ignition temperature take more time to burn while substance having high ignition temperature takes less time to burn.
  • A
    both are correct
  • B
    statement ii) is correct but i) is wrong
  • C
    statement i) is correct but ii) is wrong
    Correct
  • D
    both are wrong
12
No external heat is required to start:
  • A
    spontaneous combustion
    Correct
  • B
    splendid combustion
  • C
    spreading fire combustion
  • D
    simultaneous combustion
13
Read the following statements :i) White phosphorus ignites spontaneously at about 35\(^\circ {\text{C}}\).ii) White phosphorus is never stored under water.
  • A
    both are wrong
  • B
    both are correct
  • C
    statement i) is correct but ii) is wrong
    Correct
  • D
    statement ii) is correct but i) is wrong
14
Explosion is a result of :
  • A
    release of a large volume of gas
  • B
    both rapid combustion & release of a large volume of gas
    Correct
  • C
    incomplete combustion
  • D
    rapid combustion
15
It is due to complete combustion, that fuel burns with a:
  • A
    black flame
  • B
    blue flame
    Correct
  • C
    yellow flame
  • D
    red flame