1. For a crystal of finite size it Is found that there are 100 allowed electron energy levels at the energy E₁ in the conduction band and that the Fermi energy lies at E₁, i.e. E_F-E₁. How many electrons are there whose energy is B_F?

2. For a crystal of finite size, it is found that there are 100 allowed electron energy levels at an energy E_F Which of the following statements are correct and which are wrong, and why?

(a) Each of the 100 levels is occupied by one electron.

(b) 50 levels are empty and 50 levels are each occupied by two electrons.

(c) The first 50 levels are empty and the last 50 levels are each occupied by two electrons.

(d) The probability that each level is occupied by one electron is 0.5.

(e) 100 states are occupied by one electron each and 100 states are empty.