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
This sign if present on a parcel indicates that it is :
Question 1 figure 1
  • A
    all the above
  • B
    has high ignition temperature
  • C
    is a fossil fuel
  • D
    inflammable
    Correct
2
Read the following statements :i) As the valve of carbon dioxide fire extinguisher is opened, vapour turns into liquid.ii) Vapour carbon dioxide release from such fire extinguisher blankets the fire.
  • A
    both are correct
  • B
    statement i) is correct but ii) is wrong
  • C
    statement ii) is correct but i) is wrong
    Correct
  • D
    both are wrong
3
Following image is of fire triangle, what should be placed on its three sides?
Question 3 figure 1
  • A
    oxygen, energy, combustion
  • B
    air, heat, fuel
    Correct
  • C
    air, heat, combustion
  • D
    energy, oxygen, Carbon dioxide
4
Geeta on a Diwali light heard several explosions and asked her father about the cause. He answered :
  • A
    due to spark and incomplete combustion of combustible substance.
  • B
    due to large amount of gas creating heavy pressure
    Correct
  • C
    due to heavy pressure producing lot of fuel.
  • D
    due to rapid combustion and very low pressure.
5
Yellow flame leaves behind black residue which is also called :
  • A
    smoke
  • B
    soot
    Correct
  • C
    precipitate
  • D
    amber
6
Water is never used to extinguish an electrical fire since :i) It is bad conductor of electricity.ii) It is good conductor of electricity.
  • A
    both are wrong
  • B
    statement ii) is correct but i) is wrong
    Correct
  • C
    statement ii) is correct but i) is wrong
  • D
    both are correct
7
A foam fire extinguisher is similar in its construction to:
  • A
    all of these fire extinguishers
  • B
    soap acid fire extinguisher
  • C
    carbon dioxide fire extinguisher
  • D
    soda acid fire extinguisher
    Correct
8
Wax vapour burn completely in the :
  • A
    not in any zone of flame
  • B
    dark zone of flame
  • C
    luminous zone of flame
  • D
    non luminous zone of flame
    Correct
9
Read the following statements :i) A combustible substance that produces heat at a high cost is called fuel.ii) A combustible substance that produces heat at a low cost is called fuel.
  • A
    statement ii) is correct but i) is wrong
    Correct
  • B
    statement i) is correct but ii) is wrong
  • C
    both are correct
  • D
    both are wrong
10
Which of the following hydrocarbon is a fuel?
  • A
    \({{\text{C}}_{\mathbf{2}}}{{\text{H}}_{\mathbf{2}}}\)
  • B
    \({\text{CHC}}{{\text{l}}_{\mathbf{3}}}\)
  • C
    \({\text{C}}{{\text{H}}_{\mathbf{2}}} = {\text{C}}{{\text{H}}_{\mathbf{2}}}\)
  • D
    \({\text{C}}{{\text{H}}_{\mathbf{4}}}\)
    Correct
11
A fuel will be considered good if:
  • A
    very costly and produce lot of smoke
  • B
    ignition temperature is greater than room temperature
    Correct
  • C
    ignition temperature is lower than room temperature
  • D
    ignites easily to produce lot of carbon monoxide
12
Which of the following can catch fire on their own?
  • A
    a piece of sodium
    Correct
  • B
    a can full of kerosene
  • C
    a matchstick
  • D
    all of them
13
The least hot part of the flame is:
  • A
    red
  • B
    blue
  • C
    black
    Correct
  • D
    yellow
14
A non inflammable substance out of the following is :
  • A
    CNG
  • B
    Alcohol
  • C
    LPG
  • D
    Carbon dioxide
    Correct
15
During combustion temperature rises considerably because burning:
  • A
    rapidly
  • B
    not uses air
  • C
    uses oxygen
  • D
    produces light
    Correct