Can i do macro photoghraphy with a 50mm lense?

I'm planning to get the nikon d5300 with the 18-140mm and 50mm afs 1.8g prime lens. Is the 50mm lens suitable for macro photography?

The Nikkor 50mm f/1.8 isn't suitable for macro photography.

The AF-S Micro-Nikkor 60mm f/2.8 is a true macro lens allowing focusing to within approximately 7" of your subject and giving a full 1:1 (life-size) reproduction ratio. What this means is if you photograph an ant that measures 20mm long it will be 20mm long on your sensor.

An alternative to buying a true macro lens is to buy a set of Extension Tubes.
http://www.ephotozine.com/article/kenko-extension-tubes-for-macro-photography----nikon-af-17024

You are better off with a true macro lens, but with the 50mm you could buy extension tubes (best alternative), a reversal ring, or screw on macro filters (worst option). Even with a true macro, extension tubes are useful.

Yes you can

although the 50/1,8 is not a proper macro lense with extension tubes ( and a reversing ring for higer magnification ) you can do exellent macro photos with it

No - not on it's own. It's not a macro lens.

To do macro you either need a macro lens or alternatively you could just buy extension tubes and use the 50mm you mentioned.

No. It's not a macro lens.

To do macro photography you need a true (1:1) macro lens.

The 50mm f1.8 lens is most suitable for portraiture and general photography in low light or where a shallow depth of field is needed.

It CAN be done but it's not worth the trouble if you plan on doing macro as part of your photography interests.