Radioactive emissions

Easy

Which statement is true for isotopes of the same element? Let $Z\,$ represent the atomic number and $A\,$ represent the mass number.

$Z$ is the same but $A$ is different.

$A$ is the same but $Z$ is different.

Both $Z$ and $A$ are the same.

The difference $(A - Z)$ is the same but $Z$ is different.

Radioactive emissions Questions