Men's hats are sized according to diameter while women's are based on circumference. The most common hat size for men is 7 1/8 and for women, 221. To measure the size of a person's head, use a flexible tape measure to measure the circumference at the widest part of the head, usually an inch above the eyebrows.
Arrhenius argued that bases are neutral compounds that either dissociate or ionize in water to give OH-ions and a positive ion. NaOH is an Arrhenius base because it dissociates in water to give the hydroxide (OH -) and sodium (Na +) ions.
1 Molecules that are dissolved in water may dissociate into charged ions. 2  An acid is a substance that increases the number of H + ions in a solution. 3  A base is a substance that decreases the number of H + ions in a solution.