Chemistry
Assertion (A): 19Fluorine, 35Chlorine and 80Bromine do not constitute a Döbereiner's triad.
Reason (R): Atomic mass of chlorine is not the average mass of Fluorine and Bromine.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Periodic Table
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Answer
Both A and R are true and R is the correct explanation of A.
Explanation — The atomic masses of Fluorine is 19, Chlorine is 35 and Bromine is 80.
The mean of atomic masses of fluorine and bromine is
= = = 49.5
The obtained mean is not the atomic mass of chlorine. So, they do not constitute a Döbereiner's triad. Hence the assertion (A) is true.
Atomic mass of chlorine is not the average mass of Fluorine and Bromine. Hence the reason (R) is true.
Reason (R) justifies why florine, chlorine and bromine are not Döbereiner's triad. Hence reason (R) is the correct explanation of assertion (A).
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Related Questions
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Reason (R): The atomic mass of the middle element is the average of the masses of the other two elements.
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Reason (R): Hydrogen has two electrons in its valence shell.
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