Answer:
2 AgNO3 + Na2SO4 → Ag2SO4 + 2 NaNO3
Explanation:
The general schemefor a reaction is given as;
Reactants --> Products
In this question, the reactants are AgNO3 and Na2SO4. The product is Ag2SO4.
The equation is given as;
 AgNO3 + Na2SO4 --> Ag2SO4
The other poduct formed in this reaction is NaNO3.
The full reaction is given as;
AgNO3 + Na2SO4 --> Ag2SO4 + NaNO3
The above reaction is not balanced because there are unequal number of atoms of the elements on both sides of the reaction.
The balanced equation is given as;
2 AgNO3 + Na2SO4 → Ag2SO4 + 2 NaNO3
In this equation, there are equal number of moles of the atoms on both sides.
 
        
             
        
        
        
We are going to use Avogadro's constant to calculate how many molecules of 
carbons dioxide exist in lungs:
when 1 mole of CO2 has 6.02 x 10^23 molecules, so how many molecules in 
CO2 when the number of moles is 5 x 10^-2
number of molecules = moles of CO2 * Avogadro's number
                                     = 5 x 10^-2  * 6.02 x 10^23
                                     = 3 x 10^22 molecules 
∴ There are 3 x 10^22 molecules in CO2 exist in lungs 
        
                    
             
        
        
        
Answer:
     The mass was there all along, it was just in the air. The weight of the oxygen from the air is not weighed in the beginning, only at the end as part of the product, making it seem like there is a total mass change.