A sealed 12 m3 tank is filled with 6000 moles of ideal oxygen gas (díatomic) at an initial temperature of 270 K. The gas is heated to a final temperature of 340 K. The atomic mass
of oxygen is 16.0 gmol. The mass density of the oxygen gas, in SI units, is closest to:

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?