Which is a sign that a chemical change is occurring a: boiling
b:bubbling
c:freezing
d:melting

B. Bubbling

Explanation:

The formation of bubbles are gas fumes, which are new products. The rest are only physical changes.

B.) Bubbling

Explanation:

The usual signs of a chemical change are color changes, the formation of a precipitate, the formation of a gas, an odor change, and temperature changes. Bubbles are an example of a formation of gas.

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.