In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
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Question: Coal is mined out of the ground. Coal is pulverized into fine powder. The coal is mixed with hot air. The coal and hot air are blown into a boiler. The coal and hot air burn over a fire. Highly purified water is pumped through pipes in the boiler. The water turns into steam. The steam presses against turbines. The turbines spin. Electricity is produced. 

Answer: coal ,hot air ,water ,steam ,electricity 


Question: Fuel is converted to energy when air and petrol mix. The car engine burns the mix of air and petrol. Hot gas from the burning pushes the pistons. The resulting energy powers the crankshaft. Crankshaft powers the gears. The gears make the wheels roll. 

Answer: air ,petrol; fuel ,energy ,hot gas 


Question: Magma rises through surrounding rock. Gas bubbles form and expand, causing lots of pressure. This pressure pushes the magma through weak spots in the earth's surface,. Magma flows out as lava. This can happen slowly or in a huge explosion. 

Answer:
magma ,gas bubbles ,pressure ,lava