The structure is a phospholipid bilayer. There are many phospholipids which contain a water loving phosphate end and a water hating lipid (fatty) end. The phosphate ends all point out words while the fatty ends are inside.
The purpose is protection of the cell as well as allowing certain molecules to enter and exit the cell
A salt is an ionic compound which needs a positive charge ion and a negative ion charge to form a salt.This means that the pair of element should be a metal and non-metal.This is simply because metal atoms tend to lose negative charge electrons and form positive ions while non-metals tend to receive the electrons from the metal atom to form negative charge ions.So answer is Cl and Li.
This is false because if they are similar, then they have similar characteristics, which means they are probably from the the same class.
There are currently 24 orbiting earth
E) Energy Pyramid
Technically it's an ecological pyramid, but E seems to be the closest to that.