Learn Italian: Chi ha ideato lo scherzo non c'entra niente con questo ufficio. - Whoever devised the prank has nothing to do with this office.

C'entra comes from the pronominal verb entrarci. While entrare means 'to enter', adding the pronoun ci changes the meaning entirely to 'to have to do with' or 'to be relevant to'. In the negative phrase non c'entra niente, it translates to 'has absolutely nothing to do with'.

How does chi mean 'whoever' in this sentence? Shouldn't it be a question word?

When chi is used in a statement rather than a question, it acts as a relative pronoun meaning 'whoever', 'anyone who', or 'the person who'. Here, Chi ha ideato lo scherzo is the subject of the sentence, meaning 'The person who devised the prank'.

Why do we use the preposition con after niente here?

The preposition con is actually required by the verb entrarci. When you want to specify what someone or something is unrelated to, you use the formula entrarci con (to have to do with). Here, con questo ufficio tells us what the prankster is unrelated to.

Could I use ha inventato instead of ha ideato for 'devised'?