The earliermethod for determining the molecular weight of proteins was based on chemical analysis. The following composition of proteins were found :
Haemoglobin: 0.335% Fe
Cytochrome protein: 0.376% Fe
Peroxidase enzyme : 0.29% Se
If haemoglobin contains 4 atoms of iron, then approximate molecular mass of haemoglobin is (at. mass of Fe = 55.85)

Options

A. 16700
B. 33400
C. 66800
D. 1670

Explanation

To find the approximate molecular mass of hemoglobin based on the given information, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Information:**
- Percentage of Iron (Fe) in Hemoglobin = 0.335%
- Atomic mass of Iron (Fe) = 55.85 g/mol
- Number of Iron atoms in Hemoglobin = 4

2. **Calculate the Total Mass of Iron in One Molecule of Hemoglobin:**
- Total mass of Iron in Hemoglobin = Number of Fe atoms × Atomic mass of Fe
- Total mass of Iron = 4 × 55.85 g/mol = 223.4 g/mol

3. **Let the Molecular Mass of Hemoglobin be M:**
- We assume the molecular mass of hemoglobin is M grams per mole.

4. **Set Up the Equation Based on the Percentage Composition:**
- The percentage of Iron in Hemoglobin can be expressed as:
\[ \frac{\text{Mass of Fe in 100g of Hemoglobin}}{\text{Molecular Mass of Hemoglobin}} \times 100 = 0.335 \]
- Therefore, we can express this as:
\[ \frac{223.4}{M} \times 100 = 0.335 \]

5. **Rearranging the Equation:**
- Rearranging gives us:
\[ 223.4 \times 100 = 0.335 \times M \]
- Simplifying this:
\[ 22340 = 0.335M \]

6. **Solve for M:**
- To find M, divide both sides by 0.335:
\[ M = \frac{22340}{0.335} \approx 66716.42 \text{ g/mol} \]

7. **Approximate the Molecular Mass:**
- Rounding this value gives us approximately 66800 g/mol.

### Final Answer:
The approximate molecular mass of hemoglobin is **66800 g/mol**.