Molarity can be defined as the number of moles of solute in 1 L solution.
Molarity of Na₂SO₄ solution - 0.200 M
this means there are 0.200 moles in 1 L solution 
Molar mass of Na₂SO₄ - 142 g/mol 
therefore mass of Na₂SO₄ in 1.00 L - 0.200 mol x 142 g/mol = 28.4 g
a mass of 28.4 g of Na₂SO₄ is present in 1.00 L
        
             
        
        
        
Ans: a blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances which the body recognizes as alien, such as bacteria, viruses, and foreign substances in the blood.
        
             
        
        
        
1) START counting for sig. figs. On the FIRST non-zero digit.
2) STOP counting for sig. figs. On the LAST non-zero digit.
3) Non-zero digits are ALWAYS significant.
4) Zeroes in between two non-zero digits are significant. All other zeroes are insignificant.
        
             
        
        
        
<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 iron and copper (II) sulfate is given as:

Ionic form of the above equation follows:

As, sulfate 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.