Develop a hypothesis to explain why the radiation from the 14c source could be shielded more effectively than the radiation from the 137cs source. what do your results suggest about the decay mode of each radioactive isotope?

The results suggests that ¹³⁷C  is more radioactive and decays faster than ¹⁴C. Also ¹³⁷C penetrates more than ¹⁴C because it has both beta and gamma particle unlike ¹⁴C which has only a beta particle. Gamma particle passes to any kind of material be it fiber glass or metal unlike a beta particle, it cannot pass through these materials.