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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?
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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