banana
viper
Cedar
There is no anagram for the letters OACARO (two A, two O, R and C). The letters can spell the words orca, arc, car, coo, oar, or, and a.
Brats
You can add the letters A and R to Kansas to get Arkansas
Unique letters: 5 (L,E,T,R,S) Total letters: 7 (L,E,T,T,E,R,S)
Amber
RR
Rover
retro, retry, rural
Burma and Syria
There are no 4, 5, 6, or 7 letters words that RRRRHET can spell. The only 4 common words that can be made are: err, her, the, and he.