Density will be mass/volume= 0.2/500 = 0.0004
The sample with the lowest AVERAGE kinetic energy is
the coolest one.
The sample with the lowest TOTAL kinetic energy depends on
not only the temperature of the samples, but also on their size,
since each molecule in the sample has kinetic energy.
Explanation :
In thermodynamics, a system is region or part of space which is being studied and observed while the surrounding is the region or space around the system which interacts with the system.
Here in the experiment ,system which is observed is reaction or changes when citric acid and sodium bicarbonate are mixed together. And the mixing is carried out in the calorimeter which serves as a surrounding around the system.
The reason behind the using the calorimeter is measure the energy change occurring during the reaction.
The given question is incomplete. The complete question is:
The combustion of propane (C3H8) in the presence of excess oxygen yields 
and 
When only 2.5 mol of 
are consumed in order to complete the reaction, ________ mol of are produced.
Answer: Thus when 2.5 mol of are consumed in their reaction, 1.5 mol of are produced
Explanation:
The balanced chemical equation is:
According to stoichiometry :
5 moles of produce = 3 moles of
Thus 2.5 moles of will produce = 
moles of
Thus when 2.5 mol of are consumed in their reaction, 1.5 mol of are produced
