Both hydrogen gas and helium gas are lighter than air. why is helium used to lift blimps instead of hydrogen? a. helium has more lifting force than hydrogen because it has more electrons. b. hydrogen has less lifting force than helium because it has less mass. c. hydrogen has a tendency to lose an electron, decreasing lift. d. helium is more chemically stable than hydrogen and will not burn.

Asquare isothermal chip is of width w=5 mm on a side and is mounted in a substrate such that its side and back surfaces are well insulated; the front surface is exposed to the flow of a coolant at tinf=15 °c. from reliability considerations, the chip temperature must not exceed t=85 °c. if the coolant is air and the corresponding convection coefficient is h=200 w/m2 x k, what is the maximum allowable "power" of the chip? if the coolant is a liquid for which h=3000 w/m2 x k, what is the maximum allowable power of the chip?