Astudent wrote a chemical equation as shown.

4nh3 + 5o2 → no + h2o

what should the student do to balance the equation?

add a coefficient 7 before no and a 7 before h2o.
add a coefficient 5 before no and a 7 before h2o.
add a coefficient 4 before no and a 6 before h2o.
add a coefficient 6 before no and a 5 before h2o.

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

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation: