Hey,

Yes the  tests uploaded by NTA has different difficulty levels and have different set of questions. In certain tests they increase the difficulty level in physics and in certain they increase difficulty level in physics. So you need not to worry. These tests are basically uploaded just for your practice and stress management. And yes  test no 9 have some miscellaneous questions , which resulted in increasing it difficulty levels for certain students. Don't worry,you keep on practicing coming tests sets. Hope this helped!

Good luck.