Question

A nucleus represented by the symbol ${}_z^{A}X$ 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)

${}_Z{X}^A$ has number of protons $=Z$
and number of neutrons $=A-Z$
where $A$ is the total number of protons and neutrons
ie, $A=Z+N$ .
NOTE: The proton is nothing but the nucleus of hydrogen atom ie, a hydrogen atom from which the single orbital electron has been removed.