Question

6 g of sodium bicarbonate decomposed and loss 1.5 g of sodium bicarbonate. what is percentage of sodium bicarbonate in mixture?

Answer 1

This problem is poorly worded. I assume you have a mixture of NaHCO3 + impurities and it decomposes with a loss of 1.5 g. That loss will be due to the mass of H2O + CO2. Together that is H2CO3.
2NaHCO3 ==> Na2CO3 + H2CO3.
moles H2CO3 = grams/molar mass = 1.5/62 = 0.0242
moles NaHCO3 = 2*moles H2CO3 = 2*0.0242 = 0.0484
g NaHCO3 = mols x molar mass = 0.0484 x 84 = ?
% NaHCO3 = (g NaHCO3/6.0)*100 = ?