What is meant by the term chemical reaction

Explanation:

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⇒The composition , decomposition or displacement of molecules of matter during chemical change is called chemical reaction.

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Various conditions bring about these changes. The chemical reactions are represented by chemicalequation. The compounds or elements that take part in chemical reaction are called reactant. They are written at the left side of an arrow that represent a change while the compound or elements that formed after the chemical change are called product. They are written at the right side of the arrow.

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When nitrogen reacts with hydrogen to form ammonia :

Nitrogen + Hydrogen ⇒ Ammonia

N₂ + 3H₂ ⇒ 2NH₃

Presentation of a chemical reaction in the form of equation is called chemical equation . Chemical equation may be word equations or formula equations.

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explanation:

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.