Ch – 6 Combustion & Flame

Q.1: When a combustible substance burns on its own without the help of any external heat, it is known as ______________ combustion.

a) rapid

b) spontaneous

c) explosive

Q.2: Which of the following conditions are necessary for combustion ?

i) presence of a combustible substance.

ii) absence of a supporter of combustion.

iii) attainment of ignition temperature.

a) only iii

b) i and iii

c) ii and iii

Q.3: Which of the following has/have low ignition temperature ?

a) alcohol

b) dry grass

c) both

Q.4: A stable foam of carbon dioxide is produced due to the presence of _______________.

a) methane

b) saponin

c) none

Q.5: Which zone of the candle flame appears black and is the least hot part of the flame ?

a) innermost

b) middle

c) outermost

Q.6: LPG and CNG are examples of _________ fuels.

a) solid

b) liquid

c) gaseous

Q.7: When the inhaled carbon monoxide combines with haemoglobin of our blood, it forms _________________.

a) oxyhaemoglobin

b) carboxyhaemoglobin

c) both

Q.8: When a fuel containing hydrocarbons burns in insufficient supply of oxygen, it leads to the _____________ combustion of fuel.

a) complete

b) incomplete

c) rapid

Q.9: Which of the following are the characteristics of an ideal fuel ?

i) It should be cheap.

ii) It should be easily available.

iii) It should have a low calorific value.

iv) It should not produce any harmful gases during burning.

a) i, iii and iv

b) i, ii and iii

c) i, ii and iv

Q.10: The oxides of nitrogen combine with _____________ to form nitric acid.

a) water

b) hydrogen

c) carbon

Q.11: The calorific value of a fuel is expressed in _________________.

a) kilogram per kilojoule

b) kilojoule per kilogram

c) none

Answers:

  1. b
  2. b
  3. c
  4. b
  5. a
  6. c
  7. b
  8. b
  9. c
  10. a
  11. b

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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