Is it callous formation or callus formation?

It's the gradual build-up of tough skin in response to pressure or abrasion.

Planets are pieces of material that orbit a star such as the earth orbits the sun. Stars are 'suns' and are distributed throughout the universe. Stars are much larger than planets hence the reason...

During female meiosis, only one egg cell is formed. During male meiosis, four sperm cells are formed.

The "not un-" formation is where you qualify an adjective with the double negative "not un-" to avoid making a direct statement about something. For example, if I liked my dessert today, I might...

IONS ARE FORMED WHEN THE ATOMS WANT TO STABILIZE(THEY GIVE UP OR TAKE ELECTRONS FROM OTHER ATOMS FROM THE SURROUNDED AREA) WHEN THEY GIVE UP AN ELECTRON THE ION GETS A POSITIVE CHARGE AND WE CALL IT...