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NDA 2018 GAT · General Knowledge · Atomic Structure, Periodic Table and Bonding · easy

The atomic number of an element is equal to the number of protons in its nucleus. 2. The mass number of an atom is the sum of the number of protons…

Single correct option

Consider the following statements:
1. The atomic number of an element is equal to the number of protons in its nucleus.
2. The mass number of an atom is the sum of the number of protons and neutrons.
Which of the statements is/are correct?
  1. A. 1 only
  2. B. 2 only
  3. C. Both 1 and 2
  4. D. Neither 1 nor 2
Show answer and solution

Answer: (C) Both 1 and 2

Atomic number is defined as the number of protons, and in a neutral atom it also equals the number of electrons, so statement 1 is correct. Mass number counts nucleons, that is protons plus neutrons, since electrons have negligible mass; statement 2 is correct. Isotopes share atomic number but differ in mass number.
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Original question written in the NDA 2018 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake