A skier halfway between the top and bottom of a hill. This diagram shows a skier moving down a hill. Which statement best describes the skier? a The skier has only potential energy. b The skier has only kinetic energy. c The skier does not have potential or kinetic energy. d The skier has potential and kinetic energy.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

clouds form

solid ice forms on leaves.

water droplets form on grass.

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.

all eukaryotic cell have mitochondria : )