Solution :
In the process to isolate gold that has a 80 percent yield, a 3.00 g of Au is being isolated.
That is, the actual yield of Au is 3. 00 g
Therefore, we need to find the theoretical yield.
As we know,


As actual yield = 3.00 g
percent yield = 80 %
So, theoretical yield = 
= 3.75 g
Thus he should be able to get 3.75 g which is the theoretical yield of Au.
It is A)The smallest unit of Ne
Oxygen gas produced : 0.7 g
<h3>Further explanation</h3>
Given
10.0 grams HgO
9.3 grams Hg
Required
Oxygen gas produced
Solution
Reaction⇒Decomposition
2HgO(s)⇒2Hg(l)+O₂(g)
Conservation of mass applies to a closed system, where the masses before and after the reaction are the same
mass of reactants = mass of products
mass HgO = mass Hg + mass O₂
10 g = 9.3 g + mass O₂
mass O₂ = 0.7 g
109/8.56=12.7
50+12.7
V=62.7
Mass= Volume x Density so i divided the mass and density to get the volume. and afterwards i would just add it to the mass to get my final answer