Acolor change happens during an experiment mixing two liquids. is this a physical change or chemical change?
a. a color change always indicates a chemical change.
b. color is a physical property, so it is only a physical change.
c. a color change can be from a physical change or chemical change.
d. a color change does not mean either a physical change or chemical change.

Option (c) is the correct answer.

Explanation:

When there will be no change in chemical composition of a substance then it is known as a physical change.

For example, when ink diffuses in water then it is a physical change because no new product has formed but a color change has taken place.

On the other hand, when there occurs change in chemical composition of a substance then it is known as a chemical change.

For example, formation of carbon dioxide gas from carbon and oxygen atom is a chemical change.

In a chemical change, color change may or may not happen as it depends on the reactivity of combining substances.

Thus, we can conclude that the statement a color change can be from a physical change or chemical change, is true.

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in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

there are two significant figures.