How many moles are in 2.8x10^23 atoms of Calcium?

Consider the reaction: n2(g) + o2(g) ? 2no(g) kc = 0.10 at 2000oc starting with initial concentrations of 0.040 mol/l of n2 and 0.040 mol/l of o2, calculate the equilibrium concentration of no in mol/l how would this be done?

Which element is the least metallic between cadmium, silver, zinc, or iron?

The volume of an unknown substance in a sealed glass jar is 50 milliliters. the volume of the jar is 200 milliliters. which state of matter could the substance be?