Take note of the subscript written for each element in the compound. To find the total number of moles, make sure to multiply the subscript with the number of moles of compound. The answer for each is written below:
a. 3*1 = 3 moles Nitrogen; 3*3 = 9 moles Hydrogen
b. 0.25*2 = 0.5 moles Hydrogen; 0.25*1 = 0.25 moles Oxygen
c. 5*2 = 10 moles Hydrogen; 5*1 =5 moles Sulfur; 5*4 = 20 moles Oxygen
d. 0.75*1 = 0.75 moles Calcium; 0.75*1*2 = 1.5 moles Nitrogen; 0.75*3*2 = 4.5 moles Oxygen
I think the answer is C , more dense
1) Molarity
M = n / V
n: number of moles of solute
V: volume of the solution in liters
n = mass / molar mass = 0.000333 g / 332.32 g / mol = 1*10 ^ - 6 moles
V = 225 ml * 1 liter / 1000 ml = 0.225 liter
M = 10^-6 mol / 0.225 liter = 0.00000444 M
2) ppm
ppm = parts per million
grams of solute: 0.000333 g
grams of solution = volume * density = 225 ml * 0.785 g / ml = 176.625 g
ppm = [0.00033 g / 176.625 g] * 1,000,000 = 1.868 ppm
