Hi Hela,
If you were to comment on a tone of a particular sentence and that this one is an exclamation, would say that this sentence is written "in an exclamatory tone" ?? Possibly, although I might prefer 'in an exclamatory manner'. I might also prefer 'with an exclamatory tone'.
Is the word "tensional" appropriate in this context? If not, when is it used? I don't think I've ever heard this word. I had to check google and my dictionary to confirm it really was a word at all. Perhaps, instead, one might say something like 'tense' or 'stressed'? But I don't think an exclamation is necessarily related to tension, do you?
If you were to ask a student to justify their answers would you say "Justify your answers in sentences" ? Sounds OK to me. By the way what do you call the question that precedes an exercise? Why not simply 'a/the question'?
Best wishes, Clive