1. four, bond
2. Cohesion
3. Adhesion is correct ... looked in my bio book sorry
There are 6 elements that are the most important. The acronym, CHNOPS, is an easy way to remember these.
C - Carbon
H - Hydrogen
N - Nitrogen
O - Oxygen
P - Phosphorous
S - Sulfur
Well, I'm assuming you're talking about these terms...
Species, Genus, Family, Order, Class, Phylum, Kingdom, Domain
A good way to remember this is;
Does King Philip Come Over For Great Spaghetti
(However, this is in order from most specific to least specific)