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Question
The mass number of an element is 18. It contains 7 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?
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Solution
(b) When mass number is 18 and number of electrons is 7, then:
(i) No. of protons = No. of electrons = 7
(ii) No. of neutrons = Mass no. – No. of protons = 18 – 7 = 11
(iii)Atomic no. = 7
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