First, let's review all the substances:
- CF3COOH is called trifluoroacetic acid because, in their structure, they have a functional group that is a carboxylic acid. This is an acid.
- HNO2 would be an acid too. Specifically, it's a weak acid because it doesn't dissociate completely.
- NH4OH is a base. You can note that we have a base because this contains the OH (-) group (hydroxyl). All the derivatives of amines or ammonia would be a base.
*Note: In the carboxylic acid, we have a carbon bond with an OH (-) functional group but this carbon is also bonded to a =O (carbonyl), and that's the difference between them.
- CH3NH2 is a weak base because as we saw before, it's a derivative of amines.
- LiOH is a strong base, so it couldn't be an acid. Remember this because Li is bonded with a hydroxyl group.
The answer is that the acids are CF3COOH and HNO2.