Final answer:
The correct conditional tense form of the verb 'poner' in the given sentence is 'pondría'.
Step-by-step explanation:
The correct conditional tense form of the verb poner in the given sentence is pondría.
Therefore, the correct sentence would be: Yo pondría el libro en la mesa.
In Spanish, the conditional tense is used to express actions that would happen under certain conditions or hypothetical situations.
Learn more about Spanish verb conjugation