1. evidence of a chemical change include a. change in size b. change in color c. change in shape d. change in weight/mass 2. which of these would indicate a chemical change has occurred? a. salt dissolves in water b. a child colors a picture with a crayon c. solid iron is heated until it turns into a liquid d. a metal is added to an acid and hydrogen gas is formed

Explanation:

1).  A change that does not bring any difference in chemical composition of a substance are known as a physical change.

For example, shape, size, mass, volume, density, etc of a substance are all physical changes.

And, a change that brings difference in chemical composition of a substance is known as chemical change.

For example, precipitation, reactivity, toxicity etc are chemical changes.

Change in color also depicts a chemical change but not always.

Hence, we can conclude that evidence of a chemical change include change in color.

2).    When salt dissolves in water then it is a physical change. This is because salt dissociates into ions and does not chemically combine with water.

A child colors a picture with a crayon is also a physical change since no change in chemical composition is taking place.

Solid iron is heated until it turns into a liquid depicts change in state of substance. Hence, it is a physical change.

A metal is added to an acid and hydrogen gas is formed  shows a chemical change as formation of gas only occurs due to change in chemical composition of a substance.

Thus, we can conclude that a metal is added to an acid and hydrogen gas is formed would indicate a chemical change has occurred.

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