Molecules is the answer i believe
Density of gasoline is 0.737 g/mL and volume of tank is 13.0 gal.
Since, 1 US gal=3.78 L
Volume of tank in L will be:
Also, 1 L=1000 mL
Thus,
Mass of gasoline can be calculated as follows:
m=d×V
Here, d is density and V is volume thus,
Therefore, mass of gasoline will be 
.
Scientific investigation is the process in which scientist solve the problems by using different systematic approach. It can be initiated in different ways.
Experimental Scientific investigation: The investigation in which scientist answer the question on the basis of experimental results. Experimental investigation contains both dependent and independent variables, and only one variable is tested at a time is possible. This process makes uses of collecting observation and identifying the process in physical word.
Noting the colour of a solution when heated is the experimental scientific investigation
Therefore, other given options are part of scientific observation whereas Noting the colour of a solution when heated explains the experimental scientific investigation.
As the volume of the confined gas decreases at the constant temperature, the pressure exerted by the gas increases.
It can cause a deadly reaction to skin if not treated for a long time
