Fuels and Combustion
White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is

Pitch
Coke oven gas
Pulverised coke
Tar

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Producer gas containing least amount of tar is produced by the

Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)
High pressure gasification of coal (e.g. in Lurgi gasifier)
Partial combustion of coal
Partial combustion of large size (< 50 mm) coke

ANSWER DOWNLOAD EXAMIANS APP