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: It means that the energy is being stored or preserved to be used at a later time.
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Closed system. If the system is not closed, matter or energy can escape from the system. an example of this is if you react magnesium and hydrochloric acid in a open system. The H₂ gas is going to escape making it look like some of the mass disappeared . in that same reaction some in an open system will also loose heat to the surrounding which will make it look like less heat was produced.
Answer:
To allow all the elements or compounds to separate complete.
Explanation:
In chromatography, the compounds need some space and time to separate, one from each other, if you just use the half of the paper strip maybe you will not notice the different spots of compounds. Remember all the substances have different affinity for the solvents, that means, some react very quickly but others need more time as the colors that conform the black color in an ink.
Answer:
Explanation: Nuclear fusion