4. the mass of a single proton is approximately 1.67 x 10-27 kg. the mass of an electron is
approximately 9.11 x 104 kg. how many times bigger is a proton than an electron?

What effect would average population growth have on land usage? a. urban use of land would rise to more than 30 percent of available land. b. industrial use of land would rise to more than 30 percent of available land. c. the percentage of available land used as cropland would stay the same. d. cropland would fall to about 10 percent of available land.

Give one example of a pure (exact) number and of an estimated (measured) number.

What is the chemical formula for a compound between li and br? libr li2br libr2 libr3