$9.$ Catalytic cracking in petroleum refining enhances the production of $\_\_\_\_\_,\_\_\_,$ and $\_\_\_\_\_.$

A$)$ gasoline, diesel, kerosene

B$)$ methane, ethane, propane

C$)$ acids, bases, salts

$10.$ Fluidized bed combustion is particularly effective for $\_\_\_\_\_,$ due to its ability to operate at $\_\_\_,$ and efficiently remove $\_\_\_\_\_.$

A$)$ low$-$grade fuels, lower temperatures, pollutants

B$)$ high$-$grade fuels, higher temperatures, oxygen

C$)$ all fuel types, variable temperatures, nitrogen

$11.$ Hydrocracking is used to increase the yield of $\_\_\_\_\_,$ reduce the $\_\_\_,$ and improve the $\_\_\_\_\_$ of fuels.

A$)$ light hydrocarbons, sulfur content, cetane number

B$)$ heavy metals, viscosity, color

C$)$ biomass, carbon output, flash point

$12.$ To control emissions in a coal$-$fired power plant, technologies such as $\_\_\_\_\_,\_\_\_,$ and $\_\_\_\_\_$ are employed.

A$)$ electrostatic precipitators, scrubbers, baghouses

B$)$ catalytic converters, turbines, condensers

C$)$ pumps, valves, heaters