Which of the following conditions indicate a basic solution at 25°c?

a. poh=11.21
b. ph=9.42
c. [oh-]> [h+]
d. [oh]> 1.0 x 10^-7 m

B. , C.  and D.

Explanation:

pH is defined as the negative logarithm of the concentration of hydrogen ions.

Thus,  

pH = - log [H⁺]

pH scale generally runs from 1 to 14 where pH = 7 represents neutral medium, pH < 7 represents acidic medium and pH > 7 represents basic medium.

Also, pH + pOH = 14  

(a) So, pOH = 11.21

pH = 14 - 11.21 = 2.79

The solution is acidic.

(b) pH = 9.42

The solution is basic.

c. [OH⁻] > [H⁺]

More concentration of hydroxide ions leads to basic solution.

d. [OH⁻]> 1.0 x 10⁻⁷ M

1.0 x 10⁻⁷ M leads to neutral solution and hydroxide ions concentration greater than this yields to basic solution.