Question

A nucleus represented by the symbol ${}_Z{X}^A$ has:

• A. Z neutrons and (A - Z) protons
• B. Z protons and (A - Z) neutrons
• C. Z protons and A neutrons
• D. A protons and (Z - A) neutrons

Answer 1

Answer: (B)

In the symbol ${}_Z{X}^A,$ A gives the mass number (sum of neutrons and protons) and $Z$ the atomic number (protons). Therefore, number of neutrons $=A-Z$ .