Iodine boils at 183°c and it's vapor pressure is 100 mm hg at 116.5°c. if heat needed for fusion is 3.74 kcal/mol and the vapor pressure of its solid is 1 mm hg at 38.7°c, calculate its triple point's pressure and temperature."

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.