Atomic Structure Question 481

Question: Average atomic mass of magnesium is 24.32 amu. This Mg is composed of 79 mole % of $ ^{24}Mg $ and remaining 21 mole % of $ ^{25}Mg $ and $ ^{26}Mg $ . Calculate the mole % of $ ^{25}Mg $

Options:

A) 10%

B) 20%

C) 22%

D) 11%

Show Answer

Answer:

Correct Answer: D

Solution:

  • Idea This problem is based on mole concept. This problem can be solved by considering value of mole % of Mg as. Let mole % of $ ^{26}Mg=x $ $ \frac{(21-x)25+x(26)+79(24)}{100}=24.32 $ $ x=10 $% So, % $ ^{25}Mg=21-10=11 $ %


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