mole again

For this you need the reaction. Carbonates on heating liberate the oxide of the metal and carbon dioxide.

Ag₂CO₃ -----> Ag₂O + CO₂

As carbon dioxide escapes in gaseous form, the residue is the oxide of silver. From the reaction equation, we see that 1 mol of silver carbonate gives a residue of 1 mol oxide.
So find how many mols of carbonate 2.76 gm is. Let it be 'a' mols.

Now 1 mol of carbonate gives 1 mol of oxide.
=> 'a' mol of carbonate gives 'a' mol of oxide.

Now you have the molar mass of Ag₂O and the number of mols as well. So to find the actual weight in grams,
Weight = Molar Mass * Number of mols. = Molar Mass * 'a' grams which is your answer.

see also:: http://pubs.acs.org/doi/abs/10.1021/jp980054j

plz can u tell...
how to know about the range of temperatures in such questions .. because around 400^'C this is how the reaction proceeds:

2Ag₂CO₃ -> 4Ag + 2CO₂ + O₂

so ppt is Ag or Ag₂O.. ?

answer is 2.16 gm and it has been given already that it is STONGLY HEATED