Passage I
A mineral hydrate (MH) is an ionic compound that has associated H2O molecules. Dehydration (removal of all H2O) of an MH produces its anhydrous salt (an ionic compound that has no associated H2O molecules), which may differ in color from the MH. Table 1 shows, for each of 4 MHs, the chemical formula of one formula unit of the MH, its color, and the color of its anhydrous salt.
Figure 1 shows the mass of a sample that was converted from chalcanthite to CuSO4 as its temperature was increased from 0°C to 350°C.
Table 2 shows the solubility in H2O of each anhydrous salt at 20°C, 40°C, 60°C, and 80°C.
1. According to Table 2, which of the following graphs best shows, for each of the 4 anhydrous salts, the solubility in H2O at 80°C ?
Your Answer is
Correct Answer is D
Explanation
Looking at the data in table 2 when the temperature is 80 degrees, it is found that all the data are in the range of 43.7-66.4, and the largest value corresponds to NiSO4, so option D is in line