Let's analyze how the addition of the given compounds affects the acidity in both scenarios: (i) CuSO4 is added to a saturated (NH4)2SO4 solution: CuSO4 is a salt that can hydrolyze in solution to form an acidic solution due to the formation of H+ ions. Adding CuSO4 to a saturated (NH4)2SO4 solution will contribute additional H+ions, thus increasing the acidity of the solution. (ii) SbF5 is added to anhydrous HF : SbF5 is known as a Lewis acid, and when it is added to anhydrous HF (which itself is a weak acid) it forms a highly acidic superacid called fluoroantimonic acid (HSbF_6). This greatly increases the acidity of the mixture due to the high proton-donating ability of the resulting superacid. Therefore, in both cases, the acidity will increase upon the addition of CuSO4 and SbF5 to the respective solutions. Correct Option: A - increase, increase