MBA/PGDM

To get admission in MBA regular colleges you need to score well in the respective entrance exam:
https://www.shiksha.com/mba-masters-of-business-administration-chp

Yes, MAT score is valid for 1 year.

Hello Shweta,
Alliance University is counted among the top universities in India and offers MBA courses at the Alliance School of Business, which is ranked among the top MBA colleges in the country.

That would depend on where you want to pursue your MBA from. For top colleges you need to prepare for CAT/MAT, etc. else you can directly apply to various colleges.

You can consider following books:
Class XI and XII Mathematics by R. D. Sharma.Quantitative Aptitude for Competitive Exams by R. S. Aggarwal.
Word Power Made Easy by Norman Lewis.
Better English by Norman Lewis.

IMI, Bhubaneswar is good in all its domains, but if you talk about the Indian market, marketing has the most number of opportunities. and given IMI Bhubaneswar, it has one of the finest faculty members who guides us the most valuable things. We also have Markstats which gives you a virtual platform on marketing skills.

Checkout the course/ college review below for details:
https://www.shiksha.com/college/g-l-bajaj-institute-of-technology-and-management-greater-Noida-36186/reviews

Hello,
Our placement partners whom we are proud to be associated with are:
Hindustan Unilever, Citigroup, CRISIL Limited, D E Shaw, Darashaw, HDFC, HDFC Bank, Yes Bank, ICRA Management Consulting Services Limited, ICICI Prudential Asset Management Co. Ltd, Federal Bank, Capital First, Bank of America, Essel Group, Jet Airways, Zomato, etc. to name a few.
https://www.nldalmia.in/images/PGDM_FAQ.pdf

Hello,
Both are equally good, what matters more is which college/university is giving you the degree. A PGDM from a top-ranked college is any day more valuable than an MBA from an average university. MBA is given by a university whereas PGDM is given by a college affiliated to AICTE.