Answer:
125 carbon atoms are from proline are present in the protein.
Explanation:
Molecular formula of proline = 
Number of carbon atoms = 5
If a human protein has 25 proline monomers.
Number of proline molecules = 25
Number of carbon atoms in 25 molecules of proline :

125 carbon atoms are from proline are present in the protein.
Density = Mass / Volume
V = 1.00 * 4.00 * 2.50 = 10 cm³
22.57 g/cm³ = Mass / 10 cm³
M = 22.57 g/cm³ * 10 cm³
M = 225.7 g
Answer: The mass of the block of osmium is 225.7 g.