I would say because the respiratory system brings in the oxygen for the body and the circulatory system moves it throughout the body with the blood
Density is the ratio of mass to the volume.
The mathematical expression is given as:

Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore,
= 
Volume in mL = 
Put the values,


= 
Hence, mass of 3.8 gal of the gasoline is
.
Answer:
The three laws of Chemical Reaction are .The law of constant proportions. The law of multiple proportions. The law of reciprocal proportions.
A chemical compound is always found to be made up of the same elements combined together in the same fixed proportion by mass.
potassium and chlorine gas ---> chloride.
Hope this helps, have a good day.✌
Mass of H₂ needed to react with O₂ : 1.092 g
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Reaction
O₂(g) + 2H₂(g) → 2H₂O(g)
mass of O₂ : 8.75 g
mol O₂(MW=32 g/mol) :

From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :

Mass H₂ (MW=2 g/mol) :

Answer: because it consists of more than one element, which are hydrogen and oxygen in a covalent bond.