:shock:
"interrogative sentences" is not a suitable substitute for either of the "questions".
First of all, no native speaker would say "interrogative sentences".
Secondly, the "questions" (the first "questions") will not necessarily be asking you anything. Some may require you to solve or complete something.
Students would practice (answering)(solving)(completing) the (questions)(problems)(exercises) on the.......
I wouldn't change the second "questions".
As I understand it 'practice the questions on the exercise sheet' is not clear by itself. I guessed there was a small possibility the OP was talking about exercises related to interrogative sentences. If that was not the case, of course the OP would not accept the suggestion.
Furthermore, although I am not a native speaker, this thread had been in the queue for a long time without any answer - so I thought answering
something would bring some native speakers attention to it.
Finally I understand the expression 'interrogative sentence' is not used by native speakers in everyday English. However, I wonder whether this expression is technically used in grammar and for English teaching purposes. I have seen this expression in many ESL books. For instance: "Change the affirmative sentences to interrogative ones."
In the context above, is there another expression for 'interrogative sentences'?