Humans opinions of evolution.
Water is the only common substance that when you freeze it, it's volume INCREASES.
When the pipe originally held the "all full" volume and the the water expanded, it put a tremendous amount of pressure on the pipe. Enough pressure and the pipe would burst.
The answer for the question is c.
M(P)=3.72 g
M(P)=31 g/mol
m(Cl)=21.28 g
M(Cl)=35.5 g/mol
n(P)=m(P)/M(P)
n(P)=3.72/31=0.12 mol
n(Cl)=m(Cl)/M(Cl)
n(Cl)=21.28/35.5=0.60 mol
P : Cl = 0.12 : 0.60 = 1 : 5
PCl₅ - is the empirical formula