Proximity
> I like the proximity of my house to the school.
> The proximity of Jong won's house to school is not relevant.
Obstacle
> The obstacle is that he is not good at math.
> "What is the obstacle?"
Skyscraper
> What is the highest skyscraper in the world?
> I want to build a skyscraper.

Julie: My house is proximity to the school.
Correct: I like the proximity of my house to the school.
Explanation: You used proximity as a verb in your sentence. Proximity is a noun.

Julie: Jong won's house is not proximity to school.
Correct: The proximity of Jong won's house to school is not relevant.
Explanation: You used proximity as a verb in your sentence. Proximity is a noun.

Hello Julie! If you do not know a word, consult the dictionary. You can see there if it's a noun, verb or an adjective. Know what part of speech is the word so you can make a correct sentence. Good job, though.:)