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Class 8

Explore popular questions from Combustion and Flame for Class 8. This collection covers Combustion and Flame previous year Class 8 questions hand picked by experienced teachers.

Combustion and Flame

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Q 1. Soot is given by

A

burnt ‘C’ particles

unburnt ‘C’ particles

C

Both

D

None

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Q 2. Which of the following is not a necessary condition of combustion?

A

Presence of combustible substance

B

Presence of supporter of combustion

C

Attainment of ignition temperature of the fuel

Presence of carbon dioxide

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Q 3. The main source of sun light is

A

Nuclear fission

Nuclear fusion

C

Both

D

None of these

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Q 4. Isotope of ________is used as source of sun light.

Hydrogen

B

Oxygen

C

Chlorine

D

Lithium

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Q 5. The lowest temperature at which a substance catches fire is called as________

Ignition temperature

B

Different temperature

C

Same temperature

D

All temperature

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Q 6. The most combustible substance in matchstick is

A

{tex}P_{white}{/tex}

B

{tex}Sb_{2}S_{3}{/tex}

C

{tex}KClO_{3}{/tex}

All

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Q 7. Powdered glass and a little red phosphorus is present on ________of safety matchstick

A

Head

Rubbing surface

C

Both

D

None of these

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Q 8. Which zone produces yellow light during burning of candle?

A

Non-Luminous zone

B

Dark zone

Luminous zone

D

Blue zone

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Q 9. In Luminous zone of candle flame

Partial combustion takes place

B

Complete combustion takes place

C

both may be

D

None of these

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Q 10. The black colour of candle flame is due to

A

Sulphur

Carbon

C

{tex}CO_{2}{/tex}

D

CO

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Q 11. The coldest zone of candle wick is

Dark zone

B

Blue zone

C

Red zone

D

Yellow zone

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Q 12. What are the products of burning of magnesium?

A

MgO and heat

MgO, heat and light

C

MgO

D

None

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Q 13. Which one of the following has the highest calorific value?

{tex}H_{2}{/tex}

B

Wax

C

Candle

D

All of these

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Q 14. Which one is considered to be the most cleaner fuel

A

Bio gas

B

Marsh gas

C.N.G.

D

Petrol

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Q 15. Fischer tropsch process involves

A

Conversion of natural gas to liquid

B

Catalyst-iron and cobalt

C

High temperature 150-300°

All of these

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Q 16. Which of the following substances has the lowest ignition temperature ?

A

kerosene

spirit

C

diesel

D

mustard oil

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Q 17. Which of the following undergoes spontaneous combustion?

A

yellow sulphur

B

red phosphorus

white phosphorus

D

brown sulphur

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Q 18. Which of the following statement is not correct about carbon dioxide acting as a fire extinguisher for electrical fibers?

A

it is heavier than air

it is lighter than air

C

it is not combustible

D

it does not support combustion

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Q 19. On a cold winter night, the persons sleeping in a room with closed door and windows with a coal fire burning inside may die due to the excessive accumulation of

A

nitrogen monoxide

B

nitrogen dioxide

C

carbon dioxide

carbon monoxide

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Q 20. Which of the following fuels has the lowest calorific value?

A

Kerosene

B

CNG

Biogas

D

LPG

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Q 21. Which of the following gas does not contribute to the formation of acid rain?

A

nitrogen monoxide

carbon monoxide

C

sulphur dioxide

D

nitrogen dioxide

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Q 22. If the clothes of a person working in the kitchen catch fire, then to extinguish the fire.

A

sand should be thrown over the burning clothes

B

water should be thrown over the burning clothes

C

polyester blanket should be used to cover the burning clothes

woollen blanket should be used to cover the burning clothes

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Q 23. Which process is similar to that of a burning candle except for the difference in temperature?

A

Transpiration

Respiration

C

Evaporation

D

Sublimation

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Q 24. Which is the most common substance that can be used to put out fires ?

A

Wood

B

Petrol

Sand

D

Kerosene

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Q 25. Arrange the following fuels in order of their calorific value starting from lower to higher-

A

LPG, Kerosene, Petrol, Hydrogen

Petrol, Kerosene, LPG, Hydrogen

C

Petrol, LPG, Hydrogen, Kerosene

D

Kerosene, Petrol, LPG, Hydrogen