Which of the following is not a physical change?

dissolving salt in water

baking a cake

melting wax

freezing water

Why does the sun appear to be the brightest star in the sky? a- its apparent brightness is much greater than other stars. b- it burns more gas, making it brighter than any other star. c- it is the largest star in the galaxy, so it is the brightest star. d- its relative distance to earth is closer than the other stars.

The half-life of a certain element is 100 days. how many half-lives will it be before only one eighth of this elementremains?

In wish direction does the moving force of air flow?