Which of the following has the greatest mass? (Ar: N = 14, H = 1, O = 16, C = 12) A 2 moles of water, H2O
B 1.5 moles of ammonia, NH3
C 1 mole of hydrogen gas, H2
D 0.5 moles of methane, CH4

Silica, sio2, is formed on silicon as an electrically insulating layer for microelectronic devices. silica is formed when silicon is exposed to o2 gas at an elevated temperature. at 900˚c, it takes 90 minutes for the oxygen to diffuse from the surface to form a 0.06 micron (0.06 x 10-6 m) thick layer of sio2 on

Consider the nuclear equation below. 239 > x + 4 he 94 2 what is x? 1.235 cm 96 2.243 u 92 3.235 u 92 4.243 cm 96

Atrain travels 74 kilometers in 3 hours, and then 81 kilometers in 5 hours. what is its average speed?