Answer: balanced chemical equation: 
Net ionic equation :
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
The balanced chemical equation is:

Spectator ions are defined as the ions which does not get involved in a chemical equation or they are ions which are found on both the sides of the chemical reaction present in ionic form.
The ions which are present on both the sides of the equation are sodium and nitrate ions and hence are not involved in net ionic equation.
Hence, the net ionic equation is
in order to determine empirical formula we have to determine the mole ratio of the given elements
Let the total mass of the compound is 100g
as given that the compound has 40% sulfur , so mass of sulfur = 40g
as given that the compound has 60% oxygen, so mass of oxygen = 60g
let us calculate the moles of each element
Moles of sulfur = mass / atomic mass = 40 / 32 = 1.25
moles of oxygen = mass / atomic mass = 60/ 16 = 3.75
In order to get simple ratio of moles we will divide both the moles with least number of moles which is 1.25
moles of sulfur = 1.25 / 1.25 = 1
moles of oxygen = 3.75 /1.25 = 3
So empirical formula will be SO₃
Answer:
The importance of crystal structure. The graphite-diamond mineral pair is an extreme example of the importance of crystal structure. These two very different minerals have exactly the same chemical formula (C), but the crystal structure of the two minerals is very different. In graphite, carbon atoms are bonded together along a flat plane, as shown in Figure 3.
<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.