NCERT Exemplar Solutions Class 9 Science Solutions for Structure of the Atom - Exercise in Chapter 4 - Structure of the Atom

Question 7 Structure of the Atom - Exercise

The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

(a) 31 15 X

(b) 31 16 X

(c) 16 15 X

(d) 15 16 X


Answer is (a) 31 15 X


The number of protons in an element depicts the atomic number. A number of protons and electrons are equal in an element. Hence atomic number is written in subscript whereas the mass number is written in the subscript before the symbol of the element.

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