Is it advisable not to mention experience in an exam form from the private sector?

There is absolutely no harm in mentioning the work - experience in your application form.
If you are appearing for the Probationary - officers Examination conducted by the Banking - system, you would be scrutinised on the basis of marks of the graduation level and in no case, the aggregate irrespective of stream in the graduation level should be less than 50 percent. A relaxation of 5 percent and 10 percent would be offered to the aspirants belonging to OBC and SC/ ST candidates respectively.
Now selection would be made on the combined performance of your written and oral tests.
Hence you need to devote your time to your studies with full devotion. If you join a professional institute helping you to score impressive marks in your written test and giving much stress on your personality development in the area of better presentation of facts before the interview, it would multiply your chance of your selection.
It is immaterial whether you have shown some working experience or not.

There are two requirements in the advertisements. One is mandatory and the other is desirable. The candidate should fulfill all the mandatory requirements. If the candidate possess the desirable requirements he always has an advantage over others.

In your case it appears that experience is not a mandatory requirement and the selection is through a written test. Therefore the selection criteria would be your performance in the written test. Therefore the experience will not have any advantage at the written test stage. However you could mention the details of your experience, provided the same is relevant to the post and also you have valid documents to support the same. This will help you at the Interview stage.

You are applying for bank exam and filling the application form. Now if your work experience is not in the banking and commerce line or you have some other reasons, you can show no experience in the concerned place in the application format. That is not going to matter much.

Only problem is at some stage during interview etc they may ask you how were you occupied during these years that is after completing your education and applying for this bank exam. This is a general question and you should be prepared to answer this in a positive way. If you say that you were not getting a job that itself is a negative statement. If you say that you wanted to hide the small job you were doing it itself is a negative connotation. So you must examine this point that what advantage you will be getting by hiding this information.

The success of your result in the banking exam solely depends on your preparation for this coveted banking job and as you are aware that there is a large number of candidates appearing in this so naturally you have to work hard in order to come in the merit. If you dedicate fully for this endeavour and score significantly then whether you hide your experience or not is not going to matter anyway. So, only thing I can suggest is take this challenge with full sincerity and work hard till you succeed in your mission.

All the best.

There are two points in your question. One is a job in banking sector and the other is other jobs in private sector. Another point to be noted is last year when you applied you have mentioned your experience.

As far as bank jobs are concerned, they don't ask for any experience. So if you are mentioning also there is no difference. But if you are selected in the written test and when you attend the interview there will be a question regarding your activity after passing the examination. If you say that you are not working anywhere they may feel you are spending time wastely. To avoid that situation it is better to mention your experience in the application itself. Already you told that you have mentioned last year and you continue the same in this year also.

Coming to a job in private sector it is better to show your experience if it is relevant or not to the post you are applying. They will not consider for many posts who passed long back. So if you put your experience they will understand that you are working. If you attend an interview with some job in hand you can bargain fora better salary in private organisations.

In all the cases it will be better to mention your experience.

The banking sectors are the most delicate jobs as the employees are having an access to many private financial information of the thousands of customers & therefore on being part of such institutions carries a lot which we may refer to as the character certifications & even a bit doubt or suspicion wouldn't let you be a part of this.

One thing is important to note that for any business proposals on either side of an employee or from any employer proper details needs to get submitted & this becomes even exceptionally mandatory for any applicants in context to any profiles or companies big or small or governmental institutions or may it be the private one.

What click the mind of any interviewer or during the selection processes are the gaps & so far when you are able to explain these without creating any doubt or suspicion during any selection process should be ok & this will also ensure your consistency when you are offered with the job or else if somehow those gaps bring onto the surfaces during deputation than perhaps the implications may not work your way and therefore my suggestion to you is to be honest with your admissions in context to your education papers & experiences.