<u>Answer:</u> The net ionic equation is written below.
<u>Explanation:</u>
Net ionic equation of any reaction does not include any spectator ions.
Spectator ions are defined as the ions which does not get involved in a chemical equation. They are found on both the sides of the chemical reaction when it is present in ionic form.
The chemical equation for the reaction of ammonium carbonate and lead (II) nitrate is given as:

Ionic form of the above equation follows:

As, ammonium and nitrate ions are present on both the sides of the reaction. Thus, it will not be present in the net ionic equation and are spectator ions.
The net ionic equation for the above reaction follows:

Hence, the net ionic equation is written above.
I believe it would be the last one because you can use the molar mass of HCl to find the number of moles, then use Avogadro’s number to find the number of atoms
Hope this helps!
Amount of silver nitrate taken = 269.μmol 
Volume of the solution = 300. mL
Concentration of a solution is generally expressed in terms of molarity. Molarity is defined as the moles of a substance present per liter of the solution.

We want the concentration in millimoles/L.
Converting μmol to millimol solute:
μ
= 0.269 millimol
Volume from mL to L: 
Therefore concentration of the chemist's solution = 
Answer :Solid in bottle a is ionic, solid in bottle b is molecular and solid in bottle c is ionic.
Explanation :
Ionic compound is formed when a metal atom donates one or more electrons to a non metal. This results in the formation of a cation ( a positive ion) and an anion ( a negative ion). These ions are bonded to each other by electrostatic attraction.
The intermolecular forces in case of a an ionic compound are very strong.
The melting point of a substance depends on how strongly the molecules are attracted to each other. Stronger the forces, higher is the melting point.
Therefore ionic compounds always have very high melting points.
On the other hand, covalent compounds have weak intermolecular forces. Therefore they have low melting points.
Based on above discussion, we can classify the given compounds as follows.
a) Solid in bottle a is Ionic as it has high melting point.
b) Solid in bottle b is molecular as it has low melting point.
c) Solid in bottle c is Ionic as it has high melting point.
There is 1 mole of electrons = 96500C and Ca = 40
Ca2+ + 2e --->Ca
Base on the formula above it means that there are 2 moles of electrons to produce 1 mole of calcium.
96500C x 2 = 193000C
193000C electricity produce 40g Calcium
Coulombs = Amps x seconds (28.70A for 12 hours)
= 28.70A x 12 x 60 x 60 C
= 1 239 840 C
This amount of electricity will produce
=1239840 / 193000 x 40g Calcium
= 6.42 x 40 g Calcium
= 256.96 g
So there will be 256.96g of Calcium metal that will be produced in 12 hours.