Which of the following may happen to astronauts when they return to Earth from space? (1 point) They may feel dizzy because the flow of blood to and from the heart to the brain is affected in space.
They may feel dizzy because the heart pumps more blood per beat on Earth than in space.
Their heart rate may slow down because there is more blood to circulate around the body.
Their heart rate may slow down because there is less blood to circulate around the body.

They may feel dizzy because the flow of blood to and from the heart to the brain is affected in space.

Explanation:

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