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:

<u>Answer:</u> The chemical equation is written below.
<u>Explanation:</u>
Transmutation is defined as the process in which one chemical isotope gets converted to another chemical isotope. The number of protons or neutrons in the isotope gets changed.
The chemical equation for the reaction of curium-242 nucleus with alpha particle (helium nucleus) follows:

The product formed in the nuclear reaction are californium-245 nucleus and a neutron particle.
Mass percent= grams solute/ grams of solution x 100
Mass Percent= (50/ 150)x100= 33.3%
Answer : The pH value of an acid is below 7.
Explanation :
pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.
Mathematically,
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
When the pH less than 7 then the solution is acidic and the concentration of hydrogen ion is greater than hydroxide ion.
When the pH more than 7 then the solution is basic and the concentration of hydrogen ion is less than hydroxide ion.
When the pH is equal to 7 then the solution is neutral and the concentration of hydrogen ion is equal to the hydroxide ion.
Hence, the pH value of an acid is below 7.