This PRINCE2 e-Trainer app contains more than 450 questions. The first 38 questions are related to the PRINCE2 Overview and Principles, and are for free. To get the other questions related to all themes and process groups (in line with the exam) will cost you 7,99 Euro.The app gives you the opportunity to practice questions or to perform a mock up exam. If you chose for the practice mode you can select at question level to check immediately or check later. Immediate check will give you a brief feedback if your answer is correct or wrong. You could also check afterwards. At that moment you will get a complete rationale why an answer is correct or wrong including a reference to the official PRINCE2 manual.
Looking at the other PRINCE2 apps, this App will not bring new functionality. You get 450 questions and the rationale behind all answers.
See my other posts for the other PRINCE2 apps or select the app tag on my blog or look at the attached PRINCE2 app overview. PRINCE2 (App overview, 130416) v1