I have ipad2 so can i have siri on my ipad?

No, it's not supported on the iPad 2 - possibly because it doesn't have the noise cancellation hardware within it

Welcome to the Support Communities. iOS 7 hasn't changed the situation for Siri on iPad 2 indicated in this Apple doc:

iOS 6: Which software features does my iPhone, iPad, or iPod touch support?

...Found by searching here:

http://support.apple.com/kb/index?page=search