Citric acid and rennet are added to milk to make cheese. What is the evidence that this is a chemical reaction?
gas production
formation of a precipitate
light is released
color change​

formation of a precipitate.

Explanation:

This is because during production of cheese, citric acid is added to raise the acid level and rennet is added as an enzymes. This make the milk to coagulate and form solid and semi solids. Some part become solid part which is the cheese and the water is separated and it is called whey. That is it separated the solid from the liquid part . The precipitate is the solid part.

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.

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