Fuels and Combustion
A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon

Requires smaller combustion space and less secondary air
None of these
Is less liable to spontaneous combustion on storage
Is more difficult to ignite and produces a shorter flame

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Fuels and Combustion
Ratio of primary air to secondary air increases with increase in the rank of coal, because the

Ratio of fixed carbon to volatile matter increases
High rank coals have higher amount of volatile matter
Calorific value of the coal increases
Oxygen content progressively decreases

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