If the arrangement of atoms in a substance changes, then which of the following is true? a. a chemical reaction has occurred. b. the physical state of the substance changes. c. the chemical properties of the substance stay the same but the physical properties change. d. the physical properties of the substance stay the same but the chemical properties change.

Option (a) is the correct answer.

Explanation:

A chemical reaction is defined as the reaction in which bonds between the reactants either break or form which leads to the formation of a new substance.

For example,

Here, lithium chloride formed is a new substance which occurred due to formation of chemical bond between the reactants, that is, lithium and chlorine.

As a result, chemical properties of both reactants and products will be different.  

Thus, we can conclude that the statement a chemical reaction has occurred, is true.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

c) power lifting, will be your answer.

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