Explanation:
Number of moles(n)=Number of atoms(N)/Avogadro's constant.
Avogadro's constant=6.02×10²³
so we have
n=9.05×10²³/6.02×10²³
n=1.0503moles.
n=mass/molar mass
1.0503=mass/28
mass=1.0503×28
mass=29.4084g
Answer: The mass density is 1166.36
.
Explanation:
Given: Weight of sample in air
= 500 N
Weight of sample in alcohol
= 200 N
Specific gravity = 0.7 = 
Formula used to calculate Buoyant force is as follows.

Hence, volume of the material is calculated as follows.

where,
= Buoyant force
= specific gravity
g = acceleration due to gravity = 9.81
Substitute the values into above formula.

Now, mass of the material is calculated as follows.

Therefore, density of the material or mass density is as follows.

Thus, we can conclude that the mass density is 1166.36
.
The answer to this question I think would be 2: Better
5 hope this helps I’m pretty sure it should be right