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Assertion (A): 1 Avogram is equal to 1 amu.
Reason (R): Avogram is the reciprocal of Avogadro’s number

A. Both (A) and (R) are correct, and (R) is the correct explanation for (A).
B. Both (A) and (R) are correct, but (R) is not the correct explanation for (A).
C. (A) is correct, but (R) is incorrect.
D. (A) is incorrect, but (R) is correct.

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Last updated date: 19th Apr 2024
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Answer
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Hint: Think about the definition of Avogram and how the word seems to be formed. Also, take into account the units of both Avogram and Avogadro’s number while deducing whether the (R) statement is true or false.

Complete answer:
Let us consider the assertion, ‘Assertion (A): 1 Avogram is equal to 1amu.’
An Avogram is considered to be the value that we obtain when we divide 1 gram by the Avogadro’s number. If we consider that the mass of $6.022\times {{10}^{23}}$ atoms or molecules or a certain element weight exactly 1 gram, then while finding the avogram, we are finding the mass of every individual atom or molecule. We can see such a case in atomic hydrogen. It is said to have the mass of 1amu. Thus, 1 avogram is equal to 1amu.
Hence, (A) is true.

Consider ‘Reason (R): Avogram is the reciprocal of Avogadro’s number’
To find the value of 1 avogram, we divide one gram by the Avogadro’s number. We are dividing 1 by $6.022\times {{10}^{23}}$. But consider the units of both avogram and Avogadro’s number. When we take the reciprocal of the Avogadro’s number, the unit of the resulting value will be ‘$/molecule$’. But, when we find the value of 1 avogram, the result will have the unit $gram/molecule$ or $amu$. Thus, even if 1 avogram and the reciprocal of Avogadro’s number are numerically equal, they do not have the same unit.
Hence, (R) is false.

So, the correct answer is “Option C”.

Note: Please be careful while deducing whether the (R) statement is true or false. The fact that 1 avogram and the reciprocal of Avogadro’s number are numerically equal might be misleading. But the options, ‘A. Both (A) and (R) are correct, and (R) is the correct explanation for (A).’ and ‘B. Both (A) and (R) are correct, but (R) is not the correct explanation for (A).’ are not correct.



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