Which species has the smaller bond angle, h3o + or h2o?

To answer this question, you have to know the molecular geometry of the compound. The molecular geometry is empirical for certain compounds. For H₂O, the bond angle is 109.5°. On the other hand, the bond angle for H₃O⁺ is between 104.5° and 109.5°. So, the smaller bond angle would be H₃O⁺.