What is percentage atom economy during conversion of reactant to product if formula weight of reactants is 246 u and of product is 123 u?

Identify the change in colour when $$\mathrm{NaCl}$$ solution is titrated against $$\mathrm{AgNO}_3$$ solution using fluorescein indicator.

What is percent dissociation of acetic acid in it's $$0.01 \mathrm{~M}$$ solution if dissociation of acid is $$1.34 \times 10^{-2}$$ ?

How many molecules are present in $$22400 \mathrm{~cm}^3$$ of a gas at STP?