Which is the limiting reactant when 12.0 moles of CH. are reacted with 20.0 moles of O, in the following equation? CH. + 20. --> CO + 2H2O

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

Its not chemical its not radiation and its not convection because there is not movement of fluids so it is thermal conduction

It depends on how many moles there are, if you have about 4 moles you must divide that number by 2.5 and add 14 to it and you will get your answer.