Explanation:
The area of a circle can be evaluated by the formula
,
where 
is the radius of the circle.
Therefore, let 
,
.
Explanation:
The problem basically wants you to find a way to convert between the number of atoms present in the sample and the number of moles they are equivalent to.
To convert between atoms and moles we use something called Avogadro's constant, which basically acts as the definition of a mole.
More specifically, in order to have one mole of an element you need
6.022 x 10^23 atoms of that element. You can thus use this number as a conversion factor to take you from atoms to moles or vice versa.
In your case, you will have
3.90 x 10^ 26 atoms Zn x 1 mole Zn ( Avogrado’s constant) / 6.022 x 10^23 atoms Zn
= 6.5 x 10^8 is the answer
B) Equal to the number of protons
Answer:
alluminum has 14 neutrons
Explanation:
The way you get this is by subtracting the mass which is 27 (I rounded this) by the atomic number which is 13 to get 14 neutrons.
