In order of increasing percent water content:CoCl₂.6H₂O, Ba(OH)₂.8H₂O, MgSO₄.7H₂O
<h3>Further explanation</h3>

CoCl₂.6H₂O.MW=237.90 g/mol
6H₂O MW = 6.18=108 g/mol

MgSO₄.7H₂O.MW=246.48 g/mol
MW 7H₂O = 7.18=126 g/mol

Ba(OH)₂.8H₂O MW=315.48 g/mol
MW 8H₂O = 8.18=144 g/mol

Answer:
The answer to your question is D. 25 grams.
Answer:
The chemist would require to use 43.43 grams.
Explanation:
In order to solve this problem we need to know<u> how much do 0.550 moles of selenium weigh</u>. To do that we use selenium's<em> molar mass </em>and multiply it by the given number of moles:
- 0.550 mol * 78.96 g/mol = 43.43 g
The chemist would require to use 43.43 grams.
Answer: 13.9 g of
will be produced from the given mass of oxygen
Explanation:
To calculate the moles :

The balanced chemical reaction is:
According to stoichiometry :
7 moles of
produce = 6 moles of 
Thus 0.900 moles of
will produce =
of 
Mass of 
Thus 13.9 g of
will be produced from the given mass of oxygen
When diluting solutions from concentrated solutions the following formula can be used
c1v1 = c2v2
where c1 is concentration and v1 is volume of the concentrated solution
and c2 is concentration and v2 is volume of the diluted solution to be prepared
substituting these values
0.0813 M x 16.5 mL = 0.0200 M x V
V = 67.1 mL
the volume of the diluted solution prepared is 67.1 mL.
the volume of water that should be added to get a final volume of 67.1 mL is (67.1 - 16.5 ) = 50.6 mL
a volume fo 50.6 mL should be added