Dear



Yes you can pursue M.tech aerospace with B.tech Mechanical even through this you can diverse your expertise .



Even after M.tech in Aerospace engineering you can plan for govt jobs like Isro or DRDO of army research team





All the Best

Yes, you can go for the same as there will be no issue. And yes you will have a tough competition but it hardly matters if you are really interested in that field only.



Hope this helps!!!