If a big 2 were added in front of the formula C2 H4 O2 what would that mean

How many formula units in 2.63 mols of nacl?

An uncovered pot of water lies out in the sun. which statements correctly describe what happens at the surface of the liquid water? 1. the vapor pressure remains constant regardless of the water temperature. 2. the vapor pressure is produced by water molecules that have evaporated. 3. the vapor pressure increases as the sun heats the water in the pot. 4. evaporation stops once the vapor pressure reaches a certain point. 5. evaporation and condensation both occur on the liquid’s surface.

Consider the following system at equilibrium. caco3(s) = ca2+(aq) + co32-(aq) the addition of which compound will cause a shift in equilibrium because of a common ion effect? occia co2 cuso4 na2co3