What element below makes up 71% of the earth's crust?

Curious carl calculated the density of a cube to be 4.50 g/cm3. what is the density of the cube in g/l?

The desk has a weight of 75 lb and a center of gravity at g. determine the initial acceleration of a desk when the man applies enough force f to overcome the static friction at a and b. also, find the vertical reactions on each of the two legs at a and at b. the coefficients of static and kinetic friction at a and b are ms = 0.5 and mk = 0.2, respectively

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?