Iron is the element that is not in the cobalt subgroup.
H2O2 Is a chemical compound called hydrogen peroxide
Answer:
2.95
is the fraction of the nucleus is present in atom.
Explanation:
Given:
The diameter of the nucleus - 10A
The diameter of atom - 1.5 A
From this, we can find the radius of nucleus and atom i.e.
For nucleus 
For atom 
Now, the fraction of nucleus 
= 
or, = 
= 2.95 
Therefore, 2.95
is the fraction of nucleus in the atom.