How many moles are in a 28.35 g sample of CaCO3?

Agas at 155 kpa and standard temperature has an initial volume of 1.00 l. the pressure of the gas rises to 500 kpa as the temperature also rises to 135°c. what is the new volume? 2.16 l 0.463 l 0.207 l 4.82 l

The chemical formula for emerald is be3al2(sio3)6.an emerald can be decided as

What is the mass of 0.750 mole of aluminum oxide, al2o3?