One mole of 1,2- dibromopropane on treatment with X moles of  ${\text{NaNH}}_2$  followed by treatment with ethyl bromide gave a Pent-2-yne. The value of X is

NaNH₂ is a strong base. It mediates formation of alkyne via elimination reaction. Treatment of 1,2-dibromopropane for the formation of pentyne requires 3 moles of NaNH₂. In which 2 moles form a propyne by two consecutive eliminations of HBr. The third mole of NaNH₂ produces propyne carbanion which reacts with C₂H₅Br and forms Pentyne.