Answer is: 2. dillute acids feel slipper.
1) Acids are corrosive is correct. For example hydrochloric acid (HCl) will react with most metals.
2) Dillute acids feel slippery is not correct. Bases, for example solution of sodium hydroxide feels slipery.
3) Acids have a distinctly sour taste is correct. For example, vinegar is mixture of acetic acid (CH₃COOH) and water (H₂O). Vinegar is colourless liquid with sour taste and pungent smell, freezing point of the vinegar is lower than glacial acetic acid.
4) Acids have more hydronium ions than hydroxide ions is correct. Because acid gives a lot of hydrogen cations (H⁺), pH (pH = -log[H⁺]) is lower than seven (acidic solution).
Protein would be the main one.
