The answer is GAS. Gas has a physical state characterized by having no definite volume or shape and consisting of neutral particles. or it can also be plasma.
Phosphoric Acid - The last answer choice
Thermodynamic quantity equivalent to the total heat content of a system It is equal to the internal energy of the system plus the product of pressure and volume
Gain 1.
This is because of Chlorine's placement on the periodic table. Chlorine is a Halogen, thus being located in group 17 or 7A. This means it is one of the closest elements to being a Noble Gas or group 18/8A.
Chlorine has 7 valence electrons, and in order for it to become a Noble Gas, it needs 8. Cl- is typically the symbol used to represent this as Chlorine needs to gain an electrons instead of lose; once Chlorine gains the electron, it will be stable.
This also means that Chlorine has a high ionization energy or, in simpler terms, it would be difficult to remove an electron from Chlorine.
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the answer to this is D) They are all the same size