Question

The mass number of a nucleus is

• A. Always less than its atomic number
• B. Always more than it’s atomic number
• C. Sometimes equal to it’s atomic number
• D. Sometimes more than and sometimes equal to its atomic number

Answer 1

Answer: (D)

Sometimes more than and sometimes equal to its atomic number

Answer 2

We know that

A = number of neutrons (N) + number pf protons (Z) atomic number

In hydrogen N = 0

∴ A = Z