A visual representation of covalent bonding which represents the valence shell electrons in the molecule is said to be a Lewis structure. The lines represents the shared electron pairs and dots represents the electrons that are not involved in the bonding i.e lone pairs.
Number of valence electrons in each atom:
For Carbon, 
= 4
For Hydrogen, 
= 1
For Nitrogen, 
= 5
The Lewis structure of 
is shown in the attached image.
The formula of calculating formula charge = 
-(1)
where, F.C is formal charge, V.E is number of valence electrons, N.E is number of non-bonding electrons and B.E is number of bonding electrons.
Now, calculating the formal charge:
For on left side:
For :
For on right side:
The formula charge of each atom other than hydrogen is shown in the attached image.
Answer: The missing coefficient is 2.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
As in the products, there are 2 atoms of sodium, thus there will be 2 atoms of of sodium in the reactant as well. This will balance the number of hydrogen and oxygen atoms as well.
Thus the missing coefficient is 2.
Answer:
Mass of chemical = 1.5 mg
Explanation:
Step 1: First calculate the concentration of the stock solution required to make the final solution.
Using C1V1 = C2V2
C1 = concentration of the stock solution; V1 = volume of stock solution; C2 = concentration of final solution; V2 = volume of final solution
C1 = C2V2/V1
C1 = (6 * 25)/ 0.1
C1 = 1500 ng/μL = 1.5 μg/μL
Step 2: Mass of chemical added:
Mass of sample = concentration * volume
Concentration of stock = 1.5 μg/μL; volume of stock = 10 mL = 10^6 μL
Mass of stock = 1.5 μg/μL * 10^6 μL = 1.5 * 10^6 μg = 1.5 mg
Therefore, mass of sample = 1.5 mg
