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:

A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms.
Answer:
Increasing temperature
Explanation:

Enthalpy of the reaction = -393.5 kJ/mol
Negative sign implies that reaction is exothermic.
Effect of change in reaction condition is explained by Le chateliers principle.
According to Le chateliers principle, if the reaction conditions of a reversible reaction in a state of dynamic equilibirum is changed, the reaction will move in a direction to counteract the change.
1. Increasing the temperature
Forward reaction is exothermic that means temperature increases in forward direction. Backward reaction will be endothermic and so there is decrease in temperature in backward direction or in left direction.
On increasing temperature, reaction will be move in direction to counteract the increased temperature, therefore reaction will move in left direction.
2. Adding O2
If O2 is added, then reaction will move in a direction in which its get consumed. So, reaction will move in forward direction or in right direction.
3. Removing C (s)
Le Chatelier's principle does not apply on solids, so removal of C(s) does not affect the equilibrium.