1) What is difference between acid and base ?

Compare the composition of the moon's surface with the composition of the earth's surface.

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

Awave has a wavelength of 15 mm and a frequency of 6 hertz. what is its speed?