I am trying to do a Escape Room for science I don't get it please help me with this question is is one the pictures down below BTW I dont know what it is called, but I put it on a different thing because I dont know what science is on this thing Please Please DO NOT PUT ANY LINKS ON HERE and you are only allowed to used those upper case letters in the box 12 upper case letters

The density would be 1.622

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.

Aquantity of that isotope to decay to 1/2 of  its original value

In reversible reaction chemistry equilibrium is attained when the forward and reverse reactions are taking place at the same rate, thus, the concentrations of reactants and products remain the same. a reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. in irreversible reactions on the other hand, the reactants react to form the products, which cannot revert back into reactants.