How are acids and bases similar? why are they said to have “opposite” properties

Some of the similarities between an acid and a base are as follows:  

1. They can both conduct electricity.  

2. When dissolving an acid and a base in water, it forms ions. This property makes water a good conductor of electricity.  

3. The stronger the acid or base, the more will be the production of ions, thus, the conductivity of the solution enhances.  

4. They both can share and conduct ions.  

Some of the features due to which they are considered to exhibit opposite characteristics are as follows:  

1. The bases turn red litmus paper blue, while the acids turn blue litmus paper red.  

2. Acids usually taste sour because of the presence of H+ ions, while bases taste bitter due to the presence of OH- ions.  

3. Acids produce hydrogen ions in water, and bases give off hydroxide ions in water.  

4. Acids exhibit less pH than 7, in comparison to acids, bases exhibit greater pH than 7.  

5. The bases denature proteins, while the acids corrode active metals .

answer; i believe that the correct answer is (a) potassium(k)

if you're asking what comes out, it's steam.