Which of the following would be least acidic?Select answer from the options below1-pentyne  4-chloro-1-pentyne  2-pentyne

The acidity of a compound is determined by the stability of its conjugate base. The more stable the conjugate base, the more acidic the compound.

In the case of alkynes, the acidity is determined by the stability of the resulting alkyne anion after deprotonation. The stability of the alkyne anion is increased by electron-withdrawing groups, such as chlorine, which can stabilize the negative charge through induction.

1-pentyne is a terminal alkyne with no electron-withdrawing groups.

4-chloro-1-pentyne is a terminal alkyne with a chlorine atom, an electron-withdrawing group, on the 4th carbon.

2-pentyne is an internal alkyne with no electron-withdrawing groups.

Internal alkynes, like 2-pentyne, are less acidic than terminal alkynes because the negative charge on the carbon in the conjugate base is not as effectively stabilized.

Therefore, out of 1-pentyne, 4-chloro-1-pentyne, and 2-pentyne, 2-pentyne would be the least acidic.