The diagram below shows a substance undergoing a phase change heat The diagram shows heat being removed from the substance, causing OA. it to form a solid as its particles move farther apart OB. it to form a liquid as its particles move closer together, oc. it to form a gas as its particles move closer together. OD it to form a liquid as its particles move farther apart.

Letter a hope it

D)can be increased in a closed system

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.