When water condenses, aka changes from gas to liquid, it releases the most heat energy. Your answer is condensation.
When sulfur gain two electrons, it forms an ion with a charge of 2-
The symbol of sulfur after gaining two electrons : S2-
PV=nRT
P= ? atm
V= 2 L
T= 423 K
n= 2.3 moles
R= 0.08205
(P)(2)=(2.3)(0.08205)(423)
P= (79.826445)/(2)
P= 39.9132225 atm
That is Charles' Law. It is true for an ideal gas like helium or argon.
It is approximately true for other Gases.
I think the answer is D, PCl5. Ionic compounds are compounds made up of ions. These ions are atoms that gain or lose electrons to form a stable configuration, thus attaining a net positive charge or negative charge. Metals tend to lose electrons thus they become cations and have a net positive charge. On the other hand non-metals tend to gain electrons, forming anions that have a net negative charge. Phosphorus chloride is not an ionic compound since it is made up of phosphorus and chlorine which are both non metals.