6. The fact that ice is less dense than water is related to the fact that
ice has a molecular structure that is an open framework held together by hydrogen bonds
the molecules of ice are held to each other by covalent bonding
ice has a molecular structure in which water molecules are arranged randomly
the molecular structure of ice is much less orderly than that of water

It has to be b i hope this

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.

What are the activitys?   sorry if this took your points : (