Class 8 Science Chapter 4 HOTS Questions - Combustion and Flame

Q1. Name the compound present in the head of match stick.

a) Antimony disulphide 

b) Potassium chlorate and antimony trisulphide

c) White phosphorous and potassium chlorate

d) Red phosphorous and potassium chlorate

Q2. Which one does not burn with a flame?

a) Candle  

b) Coal  

c) Kerosene oil  

d) Molten wax

Q3. A chemical process in which a substance reacts with oxygen to give off heat is_______.

a) Photosynthesis 

b) Respiration  

c) Combustion 

d) Transpiration

Q4.In the Sun, heat and light are produced by___________________.

a) Combustion  

b) Explosion  

c) Nuclear reaction  

d) Conduction

Q5. Magnesium burns in air to produce_________.

a) Mg(OH)₂  

b) MgO  

c) MgO₂ 

d) MgCO₃

Q6. Inflammable substances have:

a) high ignition temperature 

b) low ignition temperature 

c) no ignition temperature 

d) high boiling point.

Q7. Choose the best fire extinguisher.

a) Oxygen 

b) Water 

c) Carbon dioxide 

d) Blanket

Q8. The hottest part of a candle flame:

a) luminous zone  

b) dark zone  

c) hot zone  

d) non-luminous zone.

Q9. The colour of middle zone of the candle flame is:

a) Orange 

b) Black 

c) Yellow  

d) Blue

Q10.  Complete combustion of wax vapours takes place in____________.

a) middle zone 

b) luminous zone  

c) non-luminous zone  

d) dark zone

Q11. The calorific value of wood when compared to LPG is:

a) less 

b) more  

c) same  

d) no colorific value

Q12.  The unit of calorific value is:

a) kJ/kg   

b) kg/kJ 

c) kB/kJ 

d) g/kJ

Q13.  Global warming is a result of:

a) increased O₂ 

b) increased CO₂ 

c) increased water vapour 

d) increased CO

Q14.  A very poisonous gas:

a) Carbon dioxide 

b) Nitrogen  

c) Carbon monoxide 

d) Oxygen

Q15.  A cleaner fuel for automobiles:

a) Petrol  

b) Diesel 

c) CNG 

d) LPG

Q16. This can not be used for fires involving electrical equipments:

a) Carbon dioxide 

b) Oxygen 

c) Water 

d) Fire extinguisher

Q17. A liquid fuel used in homes:

a) water 

b) LPG  

c) CNG 

d) cooking oil

Q18.  Carbon monoxide is produced by:

a) incomplete combustion of fuels   

b) explosion of fuels  

c) complete combustion of fuels  

d) sleeping in a closed room

Q19.  Sources of heat energy for domestic and industrial purposes are:

a) Matchstick   

b) fuel  

c) petrol 

d) heater

Q20.  For melting gold and silver, a gold smith uses:

a) inner most zone of a flame 

b) the least hot region

c) non-luminous zone 

d) dark zone

Q21.  The zone of partial combustion is___________.

a) luminous zone  

b) innermost zone  

c) dark zone  

d) non-luminous zone

Q22.  Use of Diesel and Petrol as fuel in automobiles is being replaced by:

a) LPG 

b) CNG 

c) Coal 

d) Bitumen

Q23.  When an electrical equipment is on fire, the best extinguisher to be used is:

a) water  

b) sunlight 

c) CO₂  

d) O₂

Q24.  What is the telephone number of fire service in Saudi Arabia?

a) 997 

b) 998  

c) 999  

d) 993

Q25.  When compared to wood the ignition temperature of kerosene oil is:

a) higher
 b) lower
 c) the same
 d) no ignition temperature

Answers:

1. b

2. b

3. c

4. c

5. b

6. b

7. c

8. d

9. c

10.c

11. b

12. a

13. b

14. c

15. c

16. c

17. b

18. a

19. c

20. c

21.a

22.b

23. c

24. b