Basically, it has been seen over years that getting a question paper would be difficult as the officials usually take the question paper back once the exam gets over.
If you have applied for NCAT, you will get a mail from the college regarding the call letter for the entire admission process and in that they attach the link for the sample paper. Otherwise doing R.S. Agarwal is the best option for preparation.
Lastly, we can say that do not rely only on sample paper, start practicing and they attach the link for the sample paper so that you get an idea regarding the same.