Radioactive decay with pennies

Explanation:

Have the class stand up. Tell them that they will be flipping the penny (you will tell them when); each time they flip one half life will have passed. If their penny lands on heads, they are radioactive and have decayed and they should sit; if their penny lands on tails, they have not decayed and may remain standing.

answer; i do believe the correct answer is (river); /// good luck

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).