The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of
isotopes X and X in the sample? (2 mark ka qus ha)
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Answers
Explanation:
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>> In order to solve this problem, we will have to suppose that the percentage of one of the isotopes in the sample is x , so that the percentage of the other isotope in the sample will be (100-x), Now :
(i) The mass of X isotope is 16 u. Suppose its percentage in the sample is x %.
(ii) The mass of X isotope is 18 u. Its percentage in the sample will be (100-x) %.
So , Average atomic mass of X = 16 × x/100 + 18 × (100-x)/100.
But the average atomic mass of X has been given to be 16 u. Therefore,
16.2 = 16 × x/100 + 18 × (100-x)/100.
16.2 = 16x + 1800 - 18x / 100
16.2 × 100 = 1800 - 2x
2x = 1800 - 1620
2x = 180
x = 180/2
x = 90
Thus the percentage of X in the sample is 90℅. The percentage of the other isotope X in the sample will be 100-90 = 10%.
Answer:
its 98 appro and 2 for other