Hello student.

Solving sample papers should be the last thing that adds to your preperation and increase in Mark's. 50 out of 70 is sone where a mid mark which is neither easy nor tough to get.

So first, learn all the concepts in ncert text book. Read it atleast 2 to 3 times. Have all the concepts on finger tips,

Then go for question papers. This is the last part of your preparation. Solve as many as you can to keep yourself on track

But solving that alone won't help much to reach your goal

First text book and then papers