Which of the following represents a chemical change? rocks being smoothed by rapid water movement the pink color of a rose iron's attraction to a magnet decomposition of stone due to acid rain

Decomposition of stone due to acid rain

Explanation:

Chemical changes are changes where new substances form due to changes in the properties of starting substances - reagents. Matters are constantly changing. When changes are only related to their state, or even to the aggregation of material, we call it the physical transformation of matter. Transformation can only be called chemistry when it results in the production of a material distinct from the initial one, with also distinct characteristics. According to this concept, we can conclude that an example of chemical change is stone decomposition due to acid rain, since acid rain is a reagent that alters the common state of the stone, causing it to decompose.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.