Effect of year back in BTech on interviews of IES, ISRO,etc.

I feel that if you score very good marks and position this one year delay effect will not do any harm to you. Have you got any valid reason for your absence from classes like illness of the member of your family or death of parents or some other genuine problem. You should be ready to answer that in case that is raised in the interview.

Anyway concentrate in your studies and think only about your objective of getting highest score and then I am sure that there will be no problem for you in your interviews for jobs at various places.

If you have not completed the course with in the stipulated time it will be a loss of one year. Naturally the question comes in the interview is why your attendance is less. You should be able to justify them with a proper proof. To come out of this problem, you can go for your M.Tech and you should complete that in time with good score and from a good college and university. Then people may not bother much about your B.Tech delay. Another way is to put up 2 or 3 years experience and then try for ISRO or any other good organisations. Try and be successful. All the best to you.

The loss of one year is not a small thing and at the time of interview this question will be definitely raised by them.
Anyway you should not feel discouraged as your performance in the course as well as your performance in the interview will be the final deciding factor for your seeking the job anywhere.
You can think of doing some specific diploma course related to your specialisation or can think of doing M Tech after completing present course and continue searching jobs also as it also has weight at the time of interview if you are pursuing higher education.

Year gap is usually considered in MNC and IT companies or Government jobs usually. But that seems to be not the case with the ISRO and the IES interviews. Those places are result oriented and they are going to focus on you delivering as per their expectations in interview. I have never heard of anyone getting denied in ISRO and IES due to the year gap. People take year gap for IIT and have drops in graduation. Only the IT field has the issue with it. Most of the other fields are not viewed with that part. So you should have no problem with this type of interviews at the ISRO and IES.

Year - gap would not be that much issue provided you are in a position to satisfy the interview with the questions being put by them in the interview.
In relation to the absorption in IES or in ISRO, you need to have preparation in a different way, the written test would involve you general awareness in current affairs, your ability to solve mathematical problems based up to graduation level, your proficiency in the reasoning test apart from your sound grasp in the stream which you have opted in Engineering. After clearing the written test, you need to appear for the oral test where your intellectual persuits would be assessed in respect of your subjects apart from your alertness.
So it would be much better to focus on your studies so as to clear both tests as indicated above. Your year - gap would not cause any hindrance.

My answer is as under:-

(a) In the written part of the selection process in IES or ISRO, you will not face any problem regarding the loss of one year.
(b) If you qualify the written examination (IES/ISRO), you should definitely expect a question on the loss of one year. If you say that you could not appear in the examination due to less percentage, there would be a negative implication. So, you have to be ready with a satisfactory explanation. You may explain this due to some family emergency, relocation of your family from one place to another place, some untoward incident which forced you to remain absent for a long period, etc. You have to convince the interview board with your answer. To convince the board, you have to prepare beforehand.
(c) However, please remember that final selection in IES or in ISRO is based upon your overall performance in both the written examination and in the interview. If your performance in the written examination is excellent, then the loss of one year won't cause much problem in the selection.

As you have already lost one year in your educational life so please study sincerely that there must not be repetition of same thing. Please concentrate on your studies to score not only good but for excellent.
In the later part of your question first you study hard to qualify the written entrance of the specified organisation, as they are too much tough. If you are selected then only you have to face the interview where this year lack question must appear. So, you must prepare for the question. Your answer must be justified to convince them enough which is important to selected finally.