[Aakash]

The question is as follows
What is the functional group in
C₂H₅OH

What do we say exactly?

The functional group is alcohol? (isn't the whole compound an alcohol)
Or
The functional group is hydroxide.( if I write only hydroxide would the answer be considered incomplete)?

[discodermolide]

This is an alcohol and the functional group is a hydroxyl group. A hydroxide implies ^-OH.
The ending -yl is usually used for functional groups, carbonyl, alkyl, alkyl, sulfonyl etc.

[Aakash]

thank you!
What is the functional group in C2H5CL?

[discodermolide]

This is an alkyl halide (generally) in this case an alkyl chloride.
By the chlorine is written Cl not CL.

[Aakash]

Is the compound an alkyl chloride or the functional group?

[discodermolide]

In this case it's an alkyl chloride.
Just like


is an aryl chloride

[Aakash]

Thank You!!!

[Babcock_Hall]

discodermolide,

In the case of the second compound, I wonder whether or not the functional group is a halogen and the class of molecule is a chloroalkane or alkyl chloride.  It seems to me that sometimes we use the same word for a functional group and a class of molecule (for example, ester), and sometimes we do not.

[discodermolide]

Yes, it is a bit ambiguous. I always called them alkyl halides. A halogen for me is the element.
That is, for example, react the alkene with a halogen to give an alkyl halide.