It is hard to fit "abstract" into a compound sentence, be careful when you do so!
The noun in the sentence is birthday, a singular, common, compound, abstract noun.
We can abstract the writer's fears in this dire situation.
He/She looks like he's/she's in an abstracted state
After his brain injury, he had trouble processing abstract ideas.
Bob was a big fan of abstract art.
Most poetry is worded in the abstract, but an abstract of poetry is a physical thing.
An adjective is a word that describes a noun or a verb. An example of a sentence that uses the word "abstract" in a sentence as an adjective would be: It is difficult for children to fully comprehend many abstract ideas.
Sodium chloride is a familiar compound.
you can use a compound sentence when i say so (by joe)
His description was very Abstract. I love abstract images.
The abstract concept of the drawing added interest to the discussion.
The nouns in the sentence, people and hall, are both concrete nouns. There are no abstract nouns in the sentence. The use of the word 'protest' is the trick. As a noun, protest is an abstract noun, but in your sentence it is the verb form 'to protest', not a noun.