What is the ph of a solution of base with a 0.051 m concentration of hydroxide ions

12.7.

Explanation:

∵ pOH = - log[OH⁻].

[OH⁻] = 0.051 M.

∴ pOH = - log[OH⁻] = - log(0.051 M) = 1.29.

∵ pH + pOH = 14.

∴ pH = 14 - pOH = 14 - 1.292 = 12.7.

i think it is d. e because the next one is igneous.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.