Answer:
Part A:
Charge is 
Configuration is 
Part B:
Charge is 
Configuration is 
Part C:
Charge is 
Configuration is 
Explanation:
Monatomic ions:
These ions consist of only one atom. If they have more than one atom then they are poly atomic ions.
Examples of Mono Atomic ions: 
Part A:
For P:
Phosphorous (P) has 15 electrons so it require 3 more electrons to stabilize itself.
Charge is 
Full ground-state electron configuration of the mono atomic ion:

Part B:
For Mg:
Magnesium (Mg) has 12 electrons so it requires 2 electrons to lose to achieve stable configuration.
Charge is 
Full ground-state electron configuration of the mono atomic ion:

Part C:
For Se:
Selenium (Se) has 34 electrons and requires two electrons to be stable.
Charge is 
Full ground-state electron configuration of the mono atomic ion:

The correct answer for the question that is being presented above is this one: "C) The reaction is spontaneous at high temperatures."
Since dH is positive and dS ~ 0 then -TdS ~ 0, meaning dG will always be greater than 0 so t<span>he reaction is spontaneous at high temperatures.</span>
Use the equation d=m/v
your mass or "m" is 78 g
your volume or "v" is 60mL
if you plug those values into the equation it will look like this:
d=78/60
d=1.3g/mL should be what you come up with