Comparing Basicity: -OCH3, -OH, -NH2, and Alkyle with Negative Charge

[catan]

Homework Statement

-OCH₃, -OH, -NH₂, and the fourth choice is an alkyle, ethyne with a neg charge. the picture shows a triple bond attacked to a hydrogen.

Homework Equations

The Attempt at a Solution

I know that OH is a relatively common base and I thought it was strong, but I have no idea how it compares with the others. I know that alkyles are are less basic than alkenes and alkanes, but the oxygens throw me off a bit. I think that by having O in them it would suggest that their conj acid would be more acidic making them more basic. Is this correct at all? Is there an easy way to determine basicity?

 

[burningbend]

check the pKa of each conjugate acid. whichever has the highest pKa is the strongest base

water = 15.7
alcohols are between 16-18
NH3 is ~35
HCCH is ~25

so NH2- is the strongest base