Answers

1.

a. 9, 9

b. 13, 13

c. 20, 20

2. K: 19; B: 5, 5; S: 16, 16; V: 23, 23

3. Boron- 11

4. Silicon- 28 must be by far the most abundant. The others must be present only in small amounts.

5. Answer not available

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