Water boils at 100 degrees Celsius
According to
Graham's Law of Diffusion," Diffusion of Gas is inversely proportional to square root of its Molecular Mass or Density".
rᵇ/rᵃ =

Or,
rᵇ/rᵃ =

----- (1)
As,
Ma = 275 g/mol
Mb = 205 g/mol
Putting Values in eq.1,
rᵇ/rᵃ =

rᵇ/rᵃ = 1.15
Result: Perfume B will diffuse 1.15 times faster than
Perfume A. Hence, Perfume B will be first smelled by the person.
Random errors will shift each measurement from its true value by a random amount and in a random direction. These will affect reliability (since they're random) but may not affect the overall accuracy of a result.
Net overall dissociation:
Na2CO3 ---> 2Na(-) + CO3(2-)
*The ion charge is in parenthesis
Answer:
The answer to your question is 92.7%
Explanation:
Balanced Chemical reaction
3 Zn + Fe₂(SO₄)₃ ⇒ 2Fe + 3ZnSO₄
Molecular weight
Zinc = 65.4 x 3 = 196.2g
Iron (III) = 56 x 2 = 112 g
Proportions
196.2 g of Zinc ------------------ 112 g of Iron
20.4 g of Zinc ----------------- x
x = (20.4 x 112) / 196.2
x = 2284.8/196.2
x = 11.65 g of Iron
% yield = 
% yield = 0.927 x 100
% yield = 92.7