Tricky Question; please answer with care and ensure its very clear please. I think the molecule might be something like hexa-1,3,5-diene?

A molecule with 5 electrons in the delocalized a molecular orbitals (MO) has the following secular matrix when applying the Hckel MO theory assumptions. - E B 0 E B - 0 B - B 0 0 0 0 B - 0 0 0 0 B E 0 0 0 0 B - / 0 0 0 0 0 0 (i) Briefly describe what is mean by the secular equations or matrix in the context of practical quantum chemistry. (ii) Explain the core approximations of Hckel MO theory with respect to the secular equations or matrix and define a and (iii) Identify the molecule with this secular matrix, giving the name and the chemical diagram. (iv) Write down the secular matrix for the same system but in a cyclic molecule instead