ekspozicio

No -ici- suffix. Esperanto has nothing of the kind, and the ending is a Latin one that arrived fused: -tio became -cio when the international vocabulary was standardised, which is why the language has stacio, nacio, revolucio, pozicio, kondiĉo's cousin tradicio and this. In every case the -ci- belongs to the borrowed word, not to Esperanto. Ekspozici- is one root. It looks decomposable because eks- is a real prefix, meaning former, and that makes the temptation worse - but eks- here is the Latin ex-, out, not the Esperanto eks-, and an ex-position is not what an exhibition is.

That contrast is worth holding beside eksedziĝi, one rank later in this same chapter, where the eks- is the real Esperanto prefix doing exactly what it says. Same three letters, two entirely different things, adjacent in the frequency list. The rule is the usual one: strip the supposed affix and ask whether what remains is a root the language has.

Using it. The verb is ekspozicii, to exhibit or put on show, and the person is an ekspoziciisto or, for the artist showing work, la ekspozicianto. Ekspoziciejo is the exhibition hall - -ej- again. For a single object on display, Esperanto says ekspoziciaĵo with the -aĵ- suffix. The plain verb montri covers showing something to one person; ekspozicii is public and deliberate.