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
If methane is burnt in sufficient oxygen the products formed are :
  • A
    carbon black and water
  • B
    carbon dioxide and water
    Correct
  • C
    oxygen and carbon dioxide
  • D
    hydrogen and carbon monoxide
2
Many harmful gases are produced during :
  • A
    incomplete combustion
    Correct
  • B
    digestion of food
  • C
    complete combustion
  • D
    rusting of iron
3
SI unit of the calorific value of a fuel is :-
  • A
    KJ/kg
  • B
    J/kg
    Correct
  • C
    KW/kg
  • D
    N/kg
4
A material that burns is one that can combine quickly with :
  • A
    water
  • B
    hydrogen
  • C
    carbon
  • D
    oxygen
    Correct
5
Middle zone of candle flame is also known as zone of :
  • A
    smoke free combustion
  • B
    impartial combustion
  • C
    partial combustion
    Correct
  • D
    complete combustion
6
Burning of a matchstick is an example of :
  • A
    spontaneous combustion
  • B
    slow combustion
  • C
    ideal combustion
  • D
    rapid combustion
    Correct
7
Fire caused by burning liquid fuels can be controlled by throwing :
  • A
    sand over it
  • B
    soil over it
  • C
    both soil over it & sand over it
    Correct
  • D
    water over it
8
No external heat is required to start :
  • A
    splendid combustion
  • B
    spontaneous combustion
    Correct
  • C
    simultaneous combustion
  • D
    spreading fire combustion
9
Burning of LPG is an example of :
  • A
    spontaneous combustion
  • B
    Both slow combustion & spontaneous combustion
  • C
    slow combustion
  • D
    rapid combustion
    Correct
10
Some substances burn on their own when kept exposed in air for some time for example :
  • A
    Phosphorus
    Correct
  • B
    Sulphur
  • C
    Carbon
  • D
    Oxygen
11
If a glass plate/slide is held into the luminous part of candle flame we see a circular blackish ring that represents:
  • A
    formation of coal
  • B
    Both burnt carbon particles & formation of coal
  • C
    unburnt carbon particles
    Correct
  • D
    burnt carbon particles
12
The colour of the hottest part of the flame is :
  • A
    orange
  • B
    yellow
  • C
    blue
    Correct
  • D
    black
13
At its ignition temperature a combustible material :
  • A
    melts
  • B
    changes into vapour
    Correct
  • C
    evolves oxygen
  • D
    extinguishes
14
Sodium can catch fire without any :
  • A
    external heat supply
    Correct
  • B
    external oxygen supply
  • C
    both external heat sup & external oxygen supply
  • D
    heat trapped in
15
It is dangerous to extinguish fire caused by an electric short circuit with the use of :
  • A
    water
    Correct
  • B
    sand
  • C
    carbon dioxide
  • D
    carbon monoxide