Answer
Sounds travel slowest in gasses so it would be air
You would want to make sure that you have controlled the variables properly, and if you determine that you did then you would repeat the experiment to be sure of the results.
<u>Answer:</u> The structure of the geometrical isomers are attached below.
<u>Explanation:</u>
Cis- and Trans- isomers are the geometrical isomers which have same chemical formula but different structural formula
According to CIP rule, the groups on the doubly bonded carbon atoms are given priorities based on the the atomic masses of first connected atom.
If the highest priority groups are on the same side, it is known as cis-form and if the highest priority groups are on opposite side, it is known as trans-form.
We are given a chemical compound, which is 2-pentene.
In this the highest priority groups are methyl and ethyl groups.
When the groups are on the same side, it forms cis-form and when the groups are on the opposite side, it forms trans-form
The structure of the geometrical isomers are attached below.
Answer: 72 grams of
are needed to completely burn 19.7 g 
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number
of particles.
To calculate the number of moles, we use the equation:

Putting in the values we get:


According to stoichiometry:
1 mole of
requires 5 moles of oxygen
0.45 moles of
require=
moles of oxygen
Mass of 
72 grams of
are needed to completely burn 19.7 g 