please tell me specifically that how much graphics AMD Mobility Raedon HD 4250 support whether 256 or 512. is there any possibility of extending graphics card for laptops
4250 is a VERY weak GPU if you're looking to play video games
extending the card - no
there's an external GPU solution, I cannot remember the name for it right now, but it's something around $300 for just casing leaving you with having to purchase a desktop gpu card.
It's called ViDock, but in order to use it the laptop must have a PC Express slot which seems to be disappearing in more recent laptops.
Unfortunately, the Radeon HD 4250 is a slow video card. Even the Intel HD 3000 graphics core found in all laptop that uses a Sandy Bridge (2nd generation) Core i3/i5/i7 is more powerful than that.