Someone drops a book on the floor, and it makes a loud noise. At that time, you turn to look at the person who dropped the book. The loud noise is an example of a… A. Hydrotropism

B. Stimulus

C. Response

D. Phototropism

Stimulus

Explanation: The definition of Stimulus is "a thing or event that evokes a specific functional reaction in an organ or tissue," according to the Oxford Dictionary. So the book dropping and causing a noise is an example of a stimulus.

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