Considering the definition of percentage by mass, the sample of pure lithium nitrate contains 7.99% lithium by mass.
<h3>Definition of percentage by mass</h3>
The percentage by mass expresses the concentration and indicates the amount of mass of solute present in 100 grams of solution.
In other words, the percentage by mass of a component of the solution is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.
The percentage by mass is calculated as the mass of the solute divided by the mass of the solution, the result of which is multiplied by 100 to give a percentage. This is:

<h3>This case</h3>
Because percent by mass indicates the ratio of solute to solution based on mass, if the sample has twice the mass of the first sample, the ratio remains constant.
So the percentage by mass is the same.
That is, the sample of pure lithium nitrate contains 7.99% lithium by mass.
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Answer:
the answer is evaporation
Explanation: Evaporation is the process by which a liquid transforms into vapor (a gas). When some material is in its liquid phase, its particles are really close together (but not as much as we would see in a metal). As the temperature of the liquid increases, also does the kinetic energy of the particles. This cause the particles in the water to move a lot faster, thus its oscillations are larger. This causes an increase in the volume of the material.