You just need to convert it into moles per Liter (mol/L).
0.0815mol / 0.550L = 0.148mol/L
The atomic number increases moving left to right across a period and subsequently so does the effective nuclear charge. Therefore, moving left to right across a period the nucleus has a greater pull on the outer electrons and the atomic radii decreases.
I would believe the answer to this question is D. According to the concept of the tragedy of the commons, shared resources are used by more than one organism. Due to the large consumption of shared resources they start to be fewer and fewer in number and over time if we are not careful they will be depleted.
Ar (argon) has 18 electrons
Cl- would give you 18 electrons
F- would give you 10 electrons
Li+ would give you 2 electrons
Na+ would give you 10 electrons
Cl- would be the correct answer