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BECE Science 2013 Paper

Question : 35

Total: 40

{}^{27}_{13}X

Solution:

Concept:

In the symbol

{}^{27}_{13}X

, the superscript is the mass number, and the subscript is the atomic number.

Explanation:

The atomic number

13

gives the number of protons in the nucleus.

So, number of protons

= 13

The mass number is the total number of protons and neutrons.

Thus,

27 = \text{protons} + \text{neutrons}

Therefore, neutrons

= 27 - 13 = 14

Answer:

The atom has

14

neutrons in its nucleus.

Correct option: B.

14

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