What is atom, isotopes and mass number?

Atomic NUmber (z): number of protons in the nuclear

Mass Number (a): total number of nucleons  in the nucleus

Isotopes have the same z but different a

Explanation:

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.