Step 1: Check each option against its standard spelling.
We scan all four words for any deviation from correct English spelling.
Step 2: Analyse option (1).
"Revarberation" is incorrect; the correct spelling is "reverberation" (re-ver-ber-a-tion). The third syllable uses 'e', not 'a'.
Step 3: Verify remaining options.
"Juxtaposition", "opaque", and "appeasement" are all spelled correctly. Option (1) is the only misspelled word.
\[ \boxed{\text{revarberation}} \]