STANDARDChemistry-Atomic Structure

STANDARD Chemistry Isotopes MCQ Question

Type: MCQ-numerical-Medium-Class 11

Two stable isotopes ⁶Li and ⁷Li have respective abundances of 7.5% and 92.5%. These isotopes have masses 6.01512 u and 7.01600 u respectively. The atomic weight of lithium is

A

6.941 u

B

3.321 u

C

2.561 u

D

0.621 u

Correct Answer

Option A

Detailed Explanation

The atomic weight is calculated as the average weight of the isotopes: (6.01512 × 7.5 + 7.01600 × 92.5)/100 = 6.941 u.

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