The half-life of zn-71 is 2.4 minutes. if one had 100.0 grams at the beginning, how many grams would be left after 7.2 minutes has elapsed?

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.

Substance a is a nonpolar liquid and has only dispersion forces among its constituent particles. substance b is also a nonpolar liquid and has about the same magnitude of dispersion forces among its constituent particles. when substance a and b are combined, they spontaneously mix.

To prevent the presence of air, noble gases are placed over highly reactive chemicals to act as inert "blanketing" gases. a chemical engineer places a mixture of noble gases consisting of 4.37 g of he, 13.36 g of ne, and 36.65 g of kr in a piston-cylinder assembly at stp. calculate the partial pressure in torr of kr.