Chlorophyll, the green colouring matter of plants responsible for photosynthesis, contains `2.68%` of magnesium by mass. Calculate the number of magnesium atoms in `2.00 g` of chlorophyll.

Options

A. `1.345xx10^(23)" atoms of Mg"`
B. `1.345xx10^(28)" atoms of Mg"`
C. `1.345xx10^(22)" atoms of Mg"`
D. `1.345xx10^(21)" atoms of Mg"`

Answer

To solve the problem of calculating the number of magnesium atoms in 2.00 g of chlorophyll, we can follow these steps:

### Step 1: Calculate the mass of magnesium in 2.00 g of chlorophyll
Given that chlorophyll contains 2.68% magnesium by mass, we can find the mass of magnesium in 2.00 g of chlorophyll using the formula:

\[ \text{Mass of Mg} = \text{Percentage of Mg} \times \text{Total mass of chlorophyll} \]

\[ \text{Mass of Mg} = 0.0268 \times 2.00 \, \text{g} = 0.0536 \, \text{g} \]

### Step 2: Calculate the number of moles of magnesium
Next, we need to convert the mass of magnesium into moles using the molar mass of magnesium, which is approximately 24 g/mol.

\[ \text{Number of moles of Mg} = \frac{\text{Mass of Mg}}{\text{Molar mass of Mg}} = \frac{0.0536 \, \text{g}}{24 \, \text{g/mol}} \approx 0.002233 \, \text{mol} \]

### Step 3: Calculate the number of magnesium atoms
To find the number of magnesium atoms, we use Avogadro's number, which is approximately \(6.022 \times 10^{23}\) atoms/mol.

\[ \text{Number of atoms of Mg} = \text{Number of moles of Mg} \times \text{Avogadro's number} \]

\[ \text{Number of atoms of Mg} = 0.002233 \, \text{mol} \times 6.022 \times 10^{23} \, \text{atoms/mol} \approx 1.34 \times 10^{21} \, \text{atoms} \]

### Final Answer
The number of magnesium atoms in 2.00 g of chlorophyll is approximately \(1.34 \times 10^{21}\) atoms.

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