i was told that you can use muric acid for removing rust....is this true and what is the process to use.

 

Muric acid is pretty strong stuff, but I wouldn't use it on rust. Plus it will definitely eat away at the paint if you don't get it all right. I wouldn't trust anything lower than a 4 on the acid/base scale. Besides if it is as strong as I think it is, it could weaken the metal underneath.

 

I wouldn't use it on the car. I bought some last year because I was told that it would clear a shower drain with ease. I wish I would have known that it would eat right through the drain plug post. After that, the metal was so weakened, I couldn't reattach the drain plug or the post would've fallen off.

 

Yes it will dissolve rust quite well. Rinse with water (or a baking soda mix). Remove the remaining residue with acetone. Scuff and treat bare metal with etching primer, galvaprime, epoxy primer, or something similar.
Muratic acid is not all that violent to metal if used with caution. Muratic acid is used as part of the process in cleaning and sealing gas tanks when using the Eastwood sealer kit. Letting it sit and sit on metal will eventually destroy it of course but, you can literally watch the rust dissolve (depending on how bad it is) and know when it's time to rinse it. There are also safer alternatives to rust removal that isn't severe (i.e. surface rust). www.eastwoodcompany.com has a few products for this. Oxisolve being my favorite for light rust.
Also I strongly recommend some form of breathing apparatus (I'm not talking about a 50¢ dust mask either) if you decide to use muratic acid in close quarters. The fumes can also burn your eyes.

 

It's actually Muriatic Acid, which is an obsolete term for Hydrochloric Acid 32%. Although Muriatic is still frequently used.

I would recommend against using it. It is a strongly corrosive acid and if you don't know what you're doing, can cause severe burns and permanent damage.