CBSE Class 8 combustionandflame — practice questions
25 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 8 combustionandflame in the app →A chemical process in which a substance reacts with oxygen to give off heat (and usually light) is called:The lowest temperature at which a combustible substance catches fire is called its:Substances which have very low ignition temperature and can easily catch fire with a flame are called:Which of the following is NOT one of the three conditions necessary for combustion?Among the following fuels, which one has the HIGHEST calorific value?CNG and LPG are widely used because they:A person whose clothes catch fire is wrapped in a blanket. The blanket helps by:Match the units: calorific value of a fuel is expressed in:Which of the following is a clear example of SPONTANEOUS combustion?Fireworks (crackers) that go off with a sudden burst of heat, light, sound and gas are an example of:Water is NOT a suitable fire extinguisher in which of the following situations?Why is CO₂ an EXCELLENT fire extinguisher, especially for electrical fires?The figure below shows the different zones of a candle flame.
. A fire eIf LPG has a calorific value of ~55 kJ/g and wood has a calorific value of ~20 kJ/g, then to obtain the same aSulphur and nitrogen in fuels are particularly harmful because, when burned, they form sulphur dioxide and oxiWhy is wood being progressively replaced by LPG in many Indian households?Carbon monoxide (CO) is particularly dangerous because:A 'good' or 'ideal' fuel should have ALL of the following properties EXCEPT:Forest fires can sometimes start without any human cause. Two natural mechanisms mentioned in the chapter are: