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The atomic mass of an element is 19. The second shell of its atom contain 7 electrons. The number of protons in its nucleus is |
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|
(a) |
9 |
(b) |
10 |
(c) |
7 |
(d) |
12 |
|
The atomic mass of an element is 19. The second shell of its atom contain 7 electrons. The number of protons in its nucleus is |
|||||||
|
(a) |
9 |
(b) |
10 |
(c) |
7 |
(d) |
12 |