After a good nights sleep, you wake up to find yourself trapped inside your room. Random
objects, made up of elements with specific
properties, have been left behind for you to
find. You must use your knowledge of the
periodic table in order to escape. Answer the
questions at each level and be sure to record
each answer. Once all four questions have
been answered, use the decoder to progress
to the next level. You must hurry and escape
your room before you end up trapped forever!

Answerhund's rule;

The correct answer to this question is 28 

Sink to the bottom. addition of potassium nitrate past it’s dissolution capacity at a particular temperature will cause the extra to just sink to the bottom of the glass.however, if you were to raise the temperature of the solution prior to dissolving it, and then slowly decrease the temperature after the dissolution, you would create a “supersaturated” solution - a solution that has more solute dissolved into it than should be allowed. if you add any extra solute past this, the entire solution would “crystallize,” and this is how you get those cool videos on youtube.