It undergoes a physical change because the matter that makes up the sidewalk does not change. THe side walk goes through a chemical and physical change because the heat makes it constrict by shacking the particles just like it happens with food
physical change I learned that from ixl when I got the question right
im not sure
physical changes
The sidewalk being warmed by the heat of the sun is a physical change not a chemical change.
When dry ice is warmed at 1 atm of pressure, it goes back to its gaseous state or form.
The chemical equation for the reaction is NH4Cl(s) + NaOH(aq) → H2O(l) + NH3(g) + NaCl(s) Ammonia gas and a solution of sodium chloride is formed.
expands
It changes color for Purple to Blue if it was heated and if it was cooled down then it will change color from purple to pink
The sidewalk being warmed by the heat of the sun is a physical change not a chemical change.
This is a physical process.
The process is a physical process and the actual change is a physical change.
Purple vapour appearing = physical
The Sun emits heat in the infrared wavelengths. The sidewalk is warmed by those direct rays.
If water is warmed up, then that means that its temperature does change.
Because the Iodine is undergoing a phase change, which is a physical change. The Iodine is going from a solid to a liquid (I presume), and it's changing color. Those are both examples of physical changes. Phase changes are easily reversible without the use of energy, you could just freeze the iodine, and have the solid again. As for the color change, that's true for a lot of elements, like Mercury. This is not an example of a chemical change because not only is it easily reversible, but because no new substance is formed. You still only have Iodine, but in a different phase, and in a different color.
built their homes
The state of matter that shows the largest change in volume when warmed or cooled is gas. Liquids and solids increase and decrease in volume in response to temperature change as well, but not to the same magnitude as gases.
secured their food
Secured their food
Secured their food