Question

Chlorophyll, a green pigment involved in the light reactions of photosynthesis, consists of 2.4312 percent $Mg$. If you are given a 100 g sample of chlorophyll, how many atoms of $Mg$ will it contain?

• A. $6.02\times {10}^{22}$ atoms
• B. $6.02\times {10}^{23}$ atoms
• C. $6.02\times {10}^{24}$ atoms
• D. $6.02\times {10}^{25}$ atoms
• E. None of the above

Answer 1

The correct option is A $6.02\times {10}^{22}$ atoms

Option $A$ is the correct answer.

Chlorophyll contains 2.4312 percentage of $Mg$ in it. Thus 100 gm of Chlorophyll will contain 2.4312 grams of $Mg$ in it.

24 grams of $Mg$ contain ${6.023\times 10}^{23}$ molecules in it

Since each molecule of $Mg$ contain one atom of $Mg$,

Thus, 24 grams of $Mg$ contain ${6.023\times 10}^{23}$ atoms in it

1 gram of $Mg$ contains ${6.023\times 10}^{23}$ $\times$ $\frac{1}{24}$ atoms in it.

Thus, 2.4312 grams of Mg contains ${6.023\times 10}^{23}$ $\times$ $\frac{1}{24}$ $\times$ $2.4312$ atoms in it which is almost equal to ${6.02\times 10}^{22}$ atoms.