Chapter 8
Journey Inside the Atom
CBSE Class 9
Science Solutions
Educart Science class Class 9 NCERT Exemplar cover
Question:

An atom has 79 protons and a mass number of 197. Calculate:

(A) Number of neutrons, and

(B) Number of electrons

Answer: Verified

Mass number (A) = Number of protons + Number of neutrons

So,

(A) Number of neutrons = 197 - 79 = 118

(B) Since the atom is neutral, the number of electrons is equal to the number of protons. Therefore, the number of electrons = 79.

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