Some Basic Concepts Of Chemistry Question 152
Question: Chlorophyll, the green colouring matter of plants responsible for photosynthesis, contains 2.68% of magnesium by mass. Calculate the number of magnesium atoms in 2.00g of chlorophyll.
Options:
A) $ 1.345\times 10^{21} $
B) $ 1.345\times 10^{20} $
C) $ 13.45\times 10^{21} $
D) $ 1.345\times 10^{23} $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] $ \because $ 100 g chlorophyll contains 2.68 g $ Mg=\frac{2.68}{24} $ mole $ Mg $
$ \therefore $ 2g chlorophyll contains $ \frac{2.68\times 2}{24\times 100} $ mol $ Mg=2.2\times {10^{-3}} $ mole $ Mg $ No. of $ Mg $ atoms $ =2.2\times {10^{-3}}\times 6.023\times 10^{23} $
$ =1.345\times 10^{21} $ atoms of $ Mg $ .
