Solve the all parts of following problem given below:

Problem: The positron is the electron's antiparticle. It has the same mass as the electron but has an opposite charge (+e). An electron and a positron can form a bound system called positronium. The system is actually unstable, because the electron and positron annihilate each other. Before the decay occurs, positronium exhibits ahydrogen-like spectrum.

Part A: How much energy is required to ionize positronium from its ground state?

Part B: What is the longest wavelength of light that will be absorbed by positronium in its ground state?

Part C: What is the distance between the electron and the positron for positronium in its ground state?

I need help to find the distance between the electron and the positron for positronium in its ground state.