What is the atomic number of the atom in the diagram above please ?

5

Explanation:

The atomic number is the number of protons in an atom. Protons are the positively charged particles in the nucleus. The number of protons define the identity of an element. An element with 5 protons is Boron, no matter how many neutrons may be present.

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.