I need help please ;) 5. The half-life of 1-131 is 8.07 days. If 25 g are left after 40.35 days, how many grams
were in the original sample?

Which is not one of the major climate zones? question 3 options: rain forest polar tropical temperate

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.

The ozone hole appears in antarctica during