Q.1: When a combustible substance burns on its own without the help of any external heat, it is known as ______________ combustion.
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 ?
b) dry grass
Q.4: A stable foam of carbon dioxide is produced due to the presence of _______________.
Q.5: Which zone of the candle flame appears black and is the least hot part of the flame ?
Q.6: LPG and CNG are examples of _________ fuels.
Q.7: When the inhaled carbon monoxide combines with haemoglobin of our blood, it forms _________________.
Q.8: When a fuel containing hydrocarbons burns in insufficient supply of oxygen, it leads to the _____________ combustion of fuel.
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.
Q.11: The calorific value of a fuel is expressed in _________________.
a) kilogram per kilojoule
b) kilojoule per kilogram