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:

Jdjdjxjjznbxyhzkaishsbzn
Kzksjdjjdidiididjdjdjj
Sksk
Answer:
NaCl + Ag(NO₃) --> Na(NO₃) + AgCl
Explanation:
Chemical equation:
NaCl + Ag(NO₃) --> Na(NO₃) + AgCl
The given reaction represent the double displacement reaction. Anion and cation of both reactant exchange with each others.
The anion of sodium chloride(Cl⁻) combine with cation of silver nitrate Ag⁺ and NO₃⁻ combine with Na⁺.
The third equation is correct while others are in correct.
Double replacement:
It is the reaction in which two compound exchange their ions and form new compounds.
AB + CD → AC +BD
SORRY CAUSE IDK IF THAT HELPED :(
Answer: Edge length of the unit cell = 628pm
Explanation: For a body centred cubic structured system, the relationship between the edge length of the unit cell and radius of the atoms in the structure is
Edge length of Unit cell (a) = (4R)/(√3)
R = 272pm = (272 × (10^-12))m = (2.72 × (10^-10))m
a = (4 × (2.72 × (10^-10)))/(√3)
a = (6.28157 × (10^-10))m = 628pm