Review the electron configurations of the elements in period 4, moving from potassium (K) to krypton (Kr). Select all the elements in period 4 that have electron configurations different from what the rules predict they should have.

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?