A sample of 2.42 g of an unknown alkali metal chloride MCl (M is - Li, Na, K, Rb, Cs or Fr) is dissolved in water. That sample is then titrated with 0.2 M AgNO3 solution. The mass of precipitate formed was 2.87 g. What is the identity of that metal? AgNO3(aq) + MCl(aq) AgCl(s) + MNO3(aq)

( M = # of moles of AgNO3 / 1 L of solution)
( n = mass/Atomic mass)