Question

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

• A. $Z$ protons and $A-Z$ neutrons
• B. $Z$ protons and $A$ neutrons
• C. $A$ protons and $Z+A$ neutrons
• D. $Z$ neutrons and $Z-A$ protons

Answer 1

The correct option is A $Z$ protons and $A-Z$ neutrons

The no. of protons in the nucleus of the atom is equal to the atomic number $\left(Z\right)$

The no. of the neutrons is equal to the difference between the mass no. of the atom $\left(A\right)$ and the Atomic no. $\left(Z\right)$

The mass no. of the atom $\left(A\right)$ is equal to the sum of the no. of protons and neutrons in the nucleus.

$A\to$ Mass number $=$ Protons$+$ neutrons

$Z=$ Atomic no. $=$ No. of protons

$\therefore Z=$ Protons,

Neutrons$=A-Z$