Question

Calculate the amount concentration of the ammonium ion in 100.0 ml of a solution containing 14.4 g of ammonium carbonate.

Answer 1

In what? mols/L, M, g/L, etc. I'll assume M or moles/L.
moles (NH4)2CO3 = grams/molar mass = ?
Then mols NH4^+ = 2 x mols (NH4)2CO3.
M = mols NH4^+/L = ?

Answer 2

3.00 mol/L