The longest word you can make using those letters once is "keyboard."
counterrevolution contains 17 letters
There is no single-word nine-letter anagram of those letters. The longest words you can make, both of eight letters, are haptenic and whitecap.
chromolithographer (18 letters) counterdemonstrator (19 letters)
Decade
The longest word starting with c is counterproductiveness with twentyone letters crystallographically has twenty letters
There is no anagram. The longest words are bulimia and bulimic (extra C or extra A).
you are rubbish arent you
Ace Ice
The missing letters F and C make the word deflects.
You can make the word Scotty out of the letters c o t y t s
The longest word is 6 letters: nocent