The correct answer is option 1: Al(OH)3(s) and Fe(OH)3(s) are both considered amphoteric compounds.

To understand why these compounds are amphoteric, we need to understand the concept of amphoteric substances. Amphoteric substances, also known as amphiprotic substances, have the ability to react as both acids and bases.

In option 1, Al(OH)3(s) and Fe(OH)3(s) are both metal hydroxides. Metal hydroxides usually have basic characteristics, as they can accept protons (H+) to form water. However, these particular metal hydroxides (Al(OH)3 and Fe(OH)3) can also donate protons, acting as acids. They can undergo reactions where they donate hydroxide ions (OH-) to form water.

Option 2, Al(OH)3(s) and HCO3-(aq), is incorrect because HCO3- (bicarbonate ion) is not an amphoteric substance. It acts as a weak base rather than an amphoteric substance.

Option 3, Ba(OH)2(s) and NaOH(aq), is incorrect because both Ba(OH)2