What is the relationship between atoms and mass?

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Nitrogen dioxide decomposes according to the reaction 2 no2(g) ⇌ 2 no(g) + o2(g) where kp = 4.48 × 10−13 at a certain temperature. if 0.70 atm of no2 is added to a container and allowed to come to equilibrium, what are the equilibrium partial pressures of no(g) and o2(g)

Achemical equilibrium between gaseous reactants and products is shown. n2(g) + 3h2(g) ⇌ 2nh3(g) how will the reaction be affected if the pressure on the system is increased? it will shift toward the reactant side as there is lower pressure on the reactant side. it will shift toward the product side as there is higher pressure on the product side. it will shift toward the reactant side as there are a greater number of moles of gas on the reactant side. it will shift toward the product side as there are a fewer number of moles of gas on the product side.