cetane number

octane number

calorific value

none of these

starts at top dead centre and ends at bottom dead centre

starts at 30 Degree before top dead centre and ends at 50 Degree before bottom dead centre

starts at 30 Degree after top dead centre and ends at 50 Degree after bottom dead centre

may start and end anywhere

75% iso-octane and 25% normal heptane

75% normal heptane and 25% iso-octane

75% petrol and 25% diesel

75% diesel and 25% petrol

half

same

double

four times

higher heating value

higher flash point

lower volatility

longer ignition delay