Phosphoric acid, H3PO4(aq), is a triprotic acid, meaning that one molecule of the acid has three acidic protons. In solution, the acid dissociates according to the 3 acid equilibria given below. Some of the species are acids or conjugate acids, some are bases or conjugate bases, and some are conjugate bases in one equilibrium equation and then acids in another! These species are called "amphoteric." Look at each species in the equilibria expressions and see if a species appears in 1) more than one equilibrium and 2) is a base in one and an acid in the other. Recall how water can be both an acid or a base and is thus amphoteric.

H3PO4(aq)↽−−⇀H+(aq)+H2PO−4(aq)

H2PO−4(aq)↽−−⇀HPO2−4(aq)+H+(aq)

HPO2−4(aq)↽−−⇀H+(aq)+PO3−4(aq)

h let me think

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance

1.43 x 10^-11 j the guy commented the awnser just making sure u see it .