Can I trade my ipad 2 for new air ipad?

No. Apple does not take trade ins.

You can sell your iPad and use the money to buy a new one.

Alternatively you can use one of Apple's recycling partners to get an Apple Store Gift card for a fraction of the iPad's worth and use that in any Apple store to buy a new iPad.

https://www.apple.com/recycling/gift-card/

You can get an estimate for your iPad here:

http://store.apple.com/us/browse/reuse_and_recycle

Depends on where you are.

Check the online Apple Store for your country.

http://store.apple.com/us/browse/open/country_selector

In good condition, with no issues or damage you can get roughly $50-$75 for it from Apple. I don't know if it's the same in your country. You can price a new iPad Air at your country's Apple Store

http://www.apple.com/retail/ipad/

Pete