Combustion and flame grade 8

Coal burns with ______

•   Flame

• Only glow

•  Both flame and glow

• None of these

The substances which have very low ignition temperature will

• Catch fire easily

• Will not catch fire

• Catch fire after some time

• None of these

Combustion is a ________

• Physical process

• Chemical process

• Both of these processes

• None of these processes

There are following zones of a flame:

• two

• three

• four

• six

Which of the following does not burn with a flame?

• Molten wax

• Kerosene oil

• Charcoal

• Camphor

  (for pest control)

Which zone of the candle flame burns with a blue flame?

• Outer zone

• Middle zone

• Innermost zone

• All of the above

Which of the following are necessary requirements for producing a fire?

• Fuel, N₂, Heat

• CO₂, Water, O₂ gas

• Fuel, O₂, Water

• Fuel, O₂, Heat

Magnesium ribbon on burning in air produces

• magnesium oxide, water and light

• magnesium oxide and heat

• magnesium oxide, heat and light

• magnesium oxide, water and heat

Substance which vaporize during Burning gives

• Combustion

• sound

• flame

• none of these

Goldsmith uses ____part of the flame for melting gold

• Outermost

• Middle

• Innermost

• Both (b) & (c)