The atomic number is 9 Ions have the same atomic number since atomic number signifies number of protons not electrons
Answer:
is the activity, measured in of a 50 mg sample of 90-Sr.
Explanation:
Half life of the 90-Sr ,
Activity coefficient of the 90-Sr = 

Mass of 90-Sr = 50 mg = 0.050 g
Molecular mass of 90-Sr = 90 g/mol
Moles of 90-Sr =
Number of atom in 0.0005555 moles of 90-Sr:


1 year = 
Activity measured in atoms per seconds:
= Number of atoms × 


Answer:
Structural formula shows the atoms and bondsin an organic compound.
Explanation:
Structural formula of methane shows
1 Carbon atom is singly bonded to 4 hydrogen atoms.
the formula for density is p=m/v
m aka the mass = 5.4; the v aka the volume = 8
so, p=5.4/8
p= 0.675 g/cm^3
*let's just say the mass' unit is gram so the unit for the density is g/cm^3
The darn answer u nimbisol is the opposite