Which one of the following is not one of the definitions of reduction? A. Reduction is the loss of oxygen from a substance.
B. Reduction is the addition of hydrogen to a substance.
C. Reduction is the gain of electrons by a substance.
D. Reduction is the loss of electrons from a substance.

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

the answer would be a