Diffusion is a general term referring to the net movement of atoms and molecules along a concentration gradient, from an area of concentration to an area of concentration.

Higher concentration to an area of lower concentration

Explanation:

When you open a perfume bottle at a corner of a room, after a while, its fragrance can be perceived across a distance at the other end of the room. This is because, molecules of the compound in the fragrance have moved from the area of higher concentration in the perfume bottle, across a concentration gradient to a region of lower concentration at the other end of the room. This is diffusion.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.