Passage III
As calcium oxalate hydrate (CaC2O4·H2O) is heated, it first dehydrates to yield calcium oxalate (CaC2O4). Next, the CaC2O4 decomposes into calcium carbonate (CaCO3) and carbon monoxide (CO). The CaCO3 then further decomposes into CaO and CO2 (see equations below).
CaC2O4·H2O(solid, s) 
CaC2O4(s) + H2O(gas, g)
CaC2O4(s)CaCO3(s) + CO(g)
CaCO3(s)CaO(s) + CO2(g)
In a thermogravimetric analysis (TGA), the mass of a sample is monitored as the sample's temperature is steadily increased. A nonreactive gas is streamed over the sample to carry away any gaseous products. The figure shows the results of a TGA of a 100 g sample of CaC2O4·H2O.
14. During the TGA, the largest change in mass resulted from the decomposition of:
Your Answer is
Correct Answer is H
Explanation
The biggest change, look at the slope, the most slanted line, the biggest change. The lines are most inclined when CaC2O4 decomposes to form CaCO3. So choose decomposition of CaC2O4