Passage VI
When compounds dissolve in water, they either give off heat to, or absorb heat from, the solution. The transfer of heat (△H) is negative (exothermic) when heat is given off, or positive (endothermic) when heat is absorbed. Figure 1 shows the △H, in kilojoules per mole (kJ/mole, where 1 mole is 6 x 1023 molecules of any compound), when Compounds A or B dissolve in water at 25°C. Solubility is the maximum amount of a compound that will dissolve in a given volume of solvent. Figures 2 and 3 show how temperature affects the solubility (in moles/L) of Compounds A and B, respectively, in water.
32. A solution is made that has concentration a of 1 mole/L of Compound A and 0.5 mole/L of Compound B. According to the passage, the number of molecules of Compound A in the solution is:
Your Answer is
Correct Answer is H
Explanation
According to the question, in 1L of solution, Compound A has 1 mole, and Compound B has 0.5 mole, so the number of molecules of A is twice that of B