Lets calculate the molecular weight of the hydrated chemical, H2C2O4.2H2O.
using the molecular masses of O=16, C=12 and H=1 gm/molar, we get
Molecular mass of the hydrated chemical = 2x1+2x12+4x16 + 2x2x1+2x16 = 126 gm/mole
and the molecular mass of water of hydration = 2x2x1 + 2x16 = 36 gm/mole
now for every 126 g hydrated chemical heated, 36 gm of water would be lost.
or, for 1.5 gm hydrated chemical, lost water = 36x1.5/126 gm = 0.429 gm
Thus, the amount of anhydrous chemical (H2C2O4) left = 1.5-0.429 gm = 1.071 gm
Therefore, the correct answer is option C: 1.071 gm.