Answer:
The answer to your question is: letter c
Explanation:
Data
V1 = 612 ml    n1 = 9.11 mol
V2 = 123 ml    n2 = ?
Formula
                                 
 
                                          
                                          
                                                 n2 = 1.83 mol                                                 
 
        
             
        
        
        
The molecular weight of hemoglobin can be calculated using osmotic pressure 
Osmotic pressure is a colligative property and it depends on molarity as
πV = nRT
where
 π = osmotic pressure
V = volume = 1mL = 0.001 L
n = moles
R = gas constant = 0.0821 L atm / mol K
T = temperature = 25°C = 25 + 273 K = 298 K
Putting values we will get value of moles

we know that

Therefore

 
        
             
        
        
        
First, we must know what happens in the precipitation reaction. This type of reaction is a double replacement reactions. It is consists of two reactant compounds which interchange cations and anions to form two products. One of the products is an insoluble solid called a precipitate. For the precipitation of CaCO₃, there are two consecutive reactions involved:
1. Slaking of quicklime, CaO
    CaO + H₂O ⇒ Ca(OH)₂
2. Precipitation
    Ca(OH)₂ + CO₂ ⇒ CaCO₃ + H₂O
The ions that make up the H₂O molecule are H⁺ and OH⁻. According to solubility rules, the cation (positively charged ion) is likely to be attracted to an anion (negatively charged ion). Together, they form an ionic bond. This type of bond is when there is a complete transfer of electrons between the two. The Ca²⁺ cation lacks 2 electrons, while the anion OH⁻ has an excess 1 electron. In order to be stable, 1 Ca²⁺ ion and 2 OH⁻ ions must combine. 
Therefore, the answer is OH⁻ ion.
        
                    
             
        
        
        
The property that determines an atom;s ability to attract electrons shared in a chemical bond is electronegativity. The correct answer is C.