Hi Gretchen, I believe it does take 21 days to change or create a habit although I think the statement should be rephrased to say it takes approximately 21 days of consistent daily behaviour combined with belief, faith, determination and emotional leverage or sincere desire to succeed to form new habits.
An example of a strong acid is hydrochloric acid. A strong acid has a pH of 1. hydrogen chloride (in water) hydrogen ion + chloride ion HCl(aq) H+(aq) + Cl-(aq). All of the hydrogen chloride molecules become hydrogen ions and chloride ions when they are dissolved in water (see examples of other strong acids).
Quick Answer. One of the main differences between acids and bases is that acids have a pH that is less than 7 and bases have a pH that is greater than 7. When dissolved in water, acids are substances that will cause the concentration of hydrogen ions (H+) to increase.