Answer: The mole ratio of oxygen to pentane for the combustion of pentane is 8 : 1.
Explanation: The given reaction is a type of combustion reaction.
Combustion reaction is a reaction in which a hydrocarbon reacts with oxygen gas to produce water and carbon dioxide gas.
For the reaction of pentane with oxygen, the balanced equation would be:

In the reaction, 1 mole of
reacts with 8 moles of
gas.
Thus giving us the mole ratio as
Oxygen : Pentane = 8 : 1
The answer is A, biogeochemical cycles.
<u>Answer:</u> The empirical and molecular formula of the compound is
and
respectively
<u>Explanation:</u>
We are given:
Mass of C = 3.758 g
Mass of H = 0.316 g
Mass of O = 1.251 g
To formulate the empirical formula, we need to follow some steps:
- <u>Step 1:</u> Converting the given masses into moles.
Moles of Carbon =
Moles of Hydrogen = 
Moles of Oxygen = 
- <u>Step 2:</u> Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.078 moles.
For Carbon = 
For Hydrogen = 
For Oxygen = 
- <u>Step 3:</u> Taking the mole ratio as their subscripts.
The ratio of C : H : O = 4 : 4 : 1
The empirical formula for the given compound is 
For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:

We are given:
Mass of molecular formula = 130 g/mol
Mass of empirical formula = 68 g/mol
Putting values in above equation, we get:

Multiplying this valency by the subscript of every element of empirical formula, we get:

Hence, the empirical and molecular formula of the compound is
and
respectively