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JAMB Chemistry 2016 Paper

Question : 10

Total: 50

\frac{7}{3}

\frac{6}{3}

Li is

Solution:

Concept:

Relative atomic mass is the weighted average of the masses of an element's isotopes according to their natural abundance.

Explanation:

Lithium has two isotopes:

\mathrm{^{7}Li}

with mass

7

and abundance

90\%

, and

\mathrm{^{6}Li}

with mass

6

and abundance

10\%

Convert each percentage into a fraction:

90\% = 0.90

and

10\% = 0.10

Contribution of

\mathrm{^{7}Li}

0.90 \times 7 = 6.3

Contribution of

\mathrm{^{6}Li}

0.10 \times 6 = 0.6

Total relative atomic mass is

6.3 + 0.6 = 6.9

Answer:

6.9

(Option D).

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