Answer is:
4. Electrons cannot be located between levels except when they are in the process of moving.
5.The limitation of the maximum number of electrons in a given energy level can be used to account for the periodic recurrence of properties as the number of electrons increases.
According to the Bohr model of the atom:
1. Electrons orbit the nucleus in orbits that have a set size and energy.
2. Energy levels of electrons are discrete (certain discrete values of energy).
3. Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).