Classification of ethanol

I know that classification of 2-methyl-2propanol is tertiary but i need help with...ethanol...2-propanol...phenol...1…

Classification is based upon the number of carbon chains linked to the carbon atom that contains the functional group. In this case , your functional group is -OH (Alcohol, Alkoxy)

1) Ethanol CH3CH2-OH C-C-OH (just showing the carbon backbone to better illustrate)

Ethanol only has one carbon attached to the "functional group" carbon, therefore, it is PRIMARY.

2) 2-Propanol CH3CHOHCH3 C-C-C
.......................................… I
.......................................… OH (It's hard to show structure here. The OH is attached to the middle carbon)

2-Propanol has two carbons linked to the "functional group" carbon, therefore , it is SECONDARY

3) 1-Phenol or Phenol is an aromatic benzene ring with one OH attached.

This one's a little tricky.. C6H5-OH

There are only two carbons attached to the "functional carbon" which makes is SECONDARY structurally. However, it' allylic which stabilizes the carbon attached to the OH to the point where it has TERTIARY character.

I would call it SECONDARY with TERTIARY stability via the allylic double bond character.