JEE Main Scores

Hey buddy sorry to say that but you cannot get MNIT with these marks as you do not have 75% in class 12th.
You are not eligible for NIT's. Try for state government engineering colleges.

I don't have any idea about IPU.
If your son has 112 marks in JEE having general category, then he might not get any good NITs easily.
He can go for other private colleges.

You can try!
As per 1st counseeling list, 50 score can get you in your 3rd-4th preferred branch. So, yes. You can try and get admission. Visit: www.thapar.edu.

Yes! Undoubtedly. Last year, at the end admissions were made open. Means, if a student hasn't filled thapar form, he/she can get admission in vacant branches. So, yes. Ofcourse. You can take admission. You don't need to wait for last round. You will get before that as per first counselling list. Visit www.thapar.edu for more information. Regards.

With this rank , the best you can get Mechanical or EEE in the NIT's other than top four that is VSNIT , MVNIT , MANIT , NIT - Jamshedpur , NIT - Surathkal , NIT durgapur . Though , you have a good rank , I would suggest you to chose better college with better stream , that is focus on college and stream both equally . Best of luck

Last year, the least marks required to get into mechanical were 101 in JEE Mains.
Hence, explore different opportunities.

Since you'll not get a government college with this rank, you can apply for a good private university such as LPU, KIIT, VIT, ICFAI, UPES, Amity, Sharda, Galgotia University, Manipal (recommended), Amrita.
Or get into one of the private colleges nearby you if you feel the placements are good.
Moreover, the last option left with you is a drop.

No, there is no such exam. Moreover, IIT-JEE is only held only for central government run institutions across the nation.

You are not likely to get a government college in India. Hence, you'll need to get either into big private universities or into local engineering institutes. Check the best colleges in PUNE for Engineering or either apply for MANIPAL, VIT, AMITY, AMRITA or LPU for distance education. NIMMS also if you can afford.