Answer:
Lithium (Li)
Explanation:
Lithium has an atomic number of 3
I think that answer you are looking for is "The Nucleus" because DNA contains genetic material but the Nucleus directs the cell.
Answer:
mass of Zn = 77.0 g
Explanation:
In the sample you have the same moles of Zn and Ga.
The formula for moles is:

Where MM: Molar Mass or Atomic Mass for elements
AM(Ga) = 69.723 amu
AM(Zn) = 65.38 amu
moles of Ga = 
mass of Zn = 
There are 10 millimeters in 1 centimeter