A substance that releases hydrogen ions in water

ions in water??

Explanation:

Acids

Explanation:

Acids are chemical compounds that release hydrogen ions (H+) when placed in water. For example, when hydrogen chloride is placed in water, it releases its hydrogen ions and the solution becomes hydrochloric acid. Bases are chemical compounds that attract hydrogen atoms when they are placed in water.

(hope this helps can i plz have brainlist :D hehe)

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

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)