please offer explanations. thank you

I) Identify the [M]+ peak in the mass spectrum shown below. m) Identify the base peak in the mass spectrum shown above. n) Circle the correct number of 'H NMR eignalo that would be expeeted for cis-1,3-dibromocyclobutane ? a) 2 b) 3 c) 4 d) 5 o) For each compound below compare the indicated protons and determine whether they are homotopic, enantiotopic or diastereotopic