please could you help with the following:

A quantum system consists of a ladder of singly degenerate energy levels with a separation of 1 energy unit, with the lowest lying level having an energy of zero. The total energy of the system is 4 energy units. i) Draw out all possible configurations of 6 molecules in this system if their total energy is 4 energy units. [4] ii) Calculate the number of microstates represented by each distribution of particles identified in part i). [3] iii) Using your results from parts i) and ii), calculate the probability of finding at least one molecule having an energy of 2 units. [3]