Scholarship / Black Hole - QuestBridge - Tell us about a concept, theory, or topic you have explored. (200 words) [3]

I feel like there is some sort of disconnect between the two paragraphs. I think you should provide a sentence or two connecting them more solidly.

Writing Feedback / [IELTS task2] Some schools are considering allowing advertisements in their buildings [3]

When you say "it could be an appropriate opinion" I feel like the word "opinion" does not fit in this context. Consider changing it to "stance" or some synonym of that.

Writing Feedback / More and more people now own cars. What are the problem and solution ? [3]

In the first sentece, i think you mean "most." Also, what do you mean by the first sentence of the second paragraph? that sentence sounds fragmented. Also, when you say "This is lound hooter that ..." it sounds informal. I think you should change that, particularly the "pissing people off" part. Overall, I think you should run this through a grammar or spell check to catch the more "wonky" sentences.