Acatastrophic disturbance that resulted in mass extinction marks the boundary of which two eras? a. precambrian time and paleozoic era b. paleozoic era and cenozoic era c. mesozoic era and cenozoic era d. none of the above

Which of the following statements about acidic water is true? a. acid has no effect on the h,o molecules. b. the solution contains a larger number of oh ions than h,o ions. c. the solution contains a larger number of h,o ions than qh ions. d. the solution contains an equal number of h,o ions and oh ions. none of the above e.