An exothermic reaction causes the surroundings to:.A. expand. B. release CO2. C. become acidic. D. decrease in temperature. E. increase in temperature

True or false:   the purpose of a defense mechanism is to get uncomfortable feelings out into the open so they can be dealt with in a healthy manner.indeed true: )

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.