WAEC Chemistry 2023 Objective — Question 25
Question 25 of 50 from the West African Examinations Council (WAEC) Chemistry 2023 Objective paper, with the correct answer and a full explanation.
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An element X has two isotopes, ⁶⁵₃₀X and ⁶⁶₃₀X with relative abundance of 60% and 40% respectively. The relative atomic mass of X is
- A. 65.00
- B. 65.40Correct
- C. 65.50
- D. 66.00
Explanation
R.A.M. = (mass₁×%₁ + mass₂×%₂)/100 = (65×60 + 66×40)/100 = (3900+2640)/100 = 6540/100 = 65.4
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