Yeah they are acceptable as a supporting financial documents but you can't apply only with that. i have seen a case who showed these saving certificates only and got rejected. They (CHC) require cash because you have to pay directly as you reach at there. NSCs take sometime to convert into cash. NSCs have specific conditions. So, I would recommend u to show B/S for a year fees and accommodation expenses. . and you can use NSC for your future or after a year financial supporting docs .