Select the correct answer.
a scientist compares two samples of white powder. one powder was present at the beginning of an experiment. the other powder was present at the end. she wants to determine whether a chemical reaction has occurred. she finds that neither sample bubbles or dissolves in water. she measures the mass and volume of the solids. sample one has a volume of 45 cm3 and a mass of 0.5 g. sample two has a volume of 65 cm3 and a mass of 1.3 g. what should the scientist conclude?
a.
the samples have the same color, so no chemical reaction has occurred.
b.
the two samples do not react with water, so no chemical reaction has occurred.
c.
the densities of the samples are different, so a chemical reaction has occurred.
d.
the densities of the samples are the same, so no chemical reaction has occurred.
e.
the densities of the samples are different, so no chemical reaction has occurred

C) The densities of the samples are different, so a chemical reaction has occurred.

Explanation:

Given,

The volume of the sample A, v = 45 cm³

The mass of the sample A, m = 0.5 g

The volume of the sample B, v = 65 cm³

The mass of the sample B, m = 1.3 g

To find the whether there is a chemical reaction has occurred, first to examine the physical properties of the samples.

The color of the samples remains the same. This will not lead to valid result. The scientist need to examine further.

Next level is to check the densities of the substance.

The density of the Sample A

                                    ρₐ = 0.5/45

                                        = 0.011 g/cm³

The density of sample B

                                      ρₓ = 1.3/65

                                          = 0.02 g/cm³

On analyzing the densities of the samples, sample A is less denser than sample B.

Hence, a chemical reaction has occurred.

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

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