How does the energy needed to overcome the energy barrier compare with the overall change in energy for this reaction?

The answer for #3 is c but i don't know why

Select all that apply. a beta particle: is electromagnetic energy is an electron has zero charge is emitted from the nucleus has a +2 charge has a -1 charge

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.