Is it possible to make pendrive as RAM in Windows-7 ?

yes you can do this but that is really not going to help you alot. as the speed of the pendrive data transfer to your processor will not be more than the speed of the harddrive. so better you just increase the space of virtual memory and this works as a RAM and resides on your hard disk.

i'm not quite sure about that. i think it might be possible. i've never done that but i think if you read up on that and do some research you might find some answers about that.

The system is known as Readyboost and has been a feature in Windows Vista as well as Windows 7. When you connect a flash drive a menu usually pops up asking what you wish to do and the option to use readyboost should be listed providing that the flash drive is fast enough. Most modern flash drives should support readyboost. If you elect to use readyboost you will be asked if you wish to use the whole drive or simply part of it, then that portion of the drive will no longer be available for data storage. To remove the feature simply delete the created file. I have tried readyboost some time ago, but not with any real improvement to the system. The idea is for Windows to use the allocated space as a swap file to support RAM.