UniqueSuper Digest-It Safe Drain Opener, 32 fl. Ounce

I have a rice clog (the offender has been "discussed" at). It is past the u bend, but drains Extremely slowly. Would this possibly work?

How do you use it to unclog a toilet? do you flush once and then hope it reaches the clogged place? or??

Is this good for hair clogs such in shower drain?

Can this be used on a travel trailer's drain system?