Central Board Of Secondary Education [CBSE] — science grade tenth

I mappearing grade tenth exam in nigeria
In our science set 2 question no 2 and 12 was out of syllabus i m sending you the question
Even teachers r not able to give right answer
Why set 1 was too easy compare to set 2 and 3
All r preparing from same book then why questions r different in all set why level is also different
Pl give gracemark for question no 2 and 12 for all the students of foreign school apparing board exam