Question

Explain why pie to pie*transition are the most spectra .explain

Answer 1

promotion of an electron from a π-bonding orbital to
an antibonding π orbital *  is denoted as a π → π * transition. 
These transitions involve moving an electron from a bonding \*pi\(
orbital to an antibonding \(\pi^*\( orbital. They tend to have molar
absorptivities on the order of 10,000 and undergo a red shift with
solvent interactions (a shift to lower energy and longer
wavelengths). This could either be due to a raising of the ground
state energy or lowering of the excited state energy. If the excited
state is polar, then it will be solvent stabilized, thus lowering its
energy and the energy of the transition. So pi to pi transition are
most.