Question

krypton or neon have a greater chance in forming momentary dipole

Answer 1

Think of it this way, momentary dipole is directly proportional to London forces, and London forces are directly proportional to the number of electrons. Since Krypton has an atomic number of 36 (36 e-) ad Neon has an atomic number of 10 (10 e-), Krypton has a higher chance of momentary dipole.