How many moles of water are produced from 0.500 moles of oxygen gas?

What semimetal can form four single covalent bonds.

Draw the structure for 5-isopropyl-2-methyl-3-nonene

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?