Answer:
0.5 M HCl -------------------lowest hydroxide ion concentration
0.1 M HNO3
HNO2 with a pH of 4.0
Water
A buffer solution with a pH of 11.0------------highest hydroxide ion concentration
Step-by-step explanation:
A solution with higher number of hydrogen ions is acidic thus has a low pH value.A solution with high number of hydroxide ions is basic thus has high value of pH.A buffer solution are those used to resist the change in the pH value of a solution when small amounts of strong acid or strong base are added.The pH value of pure water is 7 , however the normal value for pH in surface water is 6.5 to 8.5.