Thickness of strand hair = 50 μm
Diameter of an atom = 
Now, with the help of conversion factors, convert thickness in micrometer into meter i.e. 1 micrometer = 
So, thickness of strand hair =50 μm= 50 \times 10^{-6} m
Therefore,
number of atoms thick is a strand of hair = 
= 
Hence, number of atoms is
thick is a strand of hair.
To calculate percent composition, you first need to find the molar mass of C (carbon), H (hydrogen) and O (oxygen).
C is 12.01
H is 1.00
O is 16
Then multiply each by the number of atoms of each element in the formula (the number that comes after each element in the equation for example C6 means 6 carbon atoms.
C: 12.01 x 6= 72.06
H: 1x12= 12
O: 16x6= 96
Then add them up.
72.06+ 12+ 96= 180.06
Now find the percent composition of carbon.
72.06/ 180.06 x 100= 40.01%
So the answer is C 40%.
the answer to your question is A
Number of moles : n₂ = 1.775 moles
<h3>Further explanation</h3>
Given
Moles = n₁ = 1.4
Volume = V₁=22.4 L
V₂=28.4 L
Required
Moles-n₂
Solution
Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
The ratio of gas volume will be equal to the ratio of gas moles

Input the values :
n₂ = (V₂ x n₁)/V₁
n₂ = (28.4 x 1.4)/22.4
n₂ = 1.775 moles
A feature that an iron metal has is a sea of electrons