some que's

For Q 1
It should be B.
from one we cant say if n is an integer.let n = root 3;then n^2 = 3.But n is not an integer.If n^2 = 9 n is an integer.So A is not SUFF.
If you check B; If root n is an integer this means n is a perfect square and hence it has to be integer

For Q 2
IMO E
From A we get two options
Either n^3 <0 and 1 - x^2 >0 OR n^3 > 0 and 1 - x^2 < 0.
This does not give any clue if x is only negative

From B also we get the condition that -1 < x < 1. hence cant say.
If we combine both ; then also we are unable to determine.
hence E