1) A potassium carbonate hydrate has a formula K2CO3.XH2O. 10g of the hydrate leave 7.83g of anhydrous salt upon heating. Deduce the formula of the hydrate.
2) Samples of carbon of masses 3.62g , 5.91g , and 7.07g undergo combustion in excess air. The masses of carbon dioxide (the unique product of the combustion in each case) obtained are respectively 13.26g, 21.66g, and 25.91g. Does carbon dioxide have a fixed composition? Determine it!