20. A+Barrow HCequiv CHxrightarrow [Delta ](NaHI)arrow A(CH_(3)I)/(-272)arrow B(NaNH_(2))/(-272)arrow Cxrightarrow [-C](CH_(3)I)arrow D(H_(2)O)/(H_(2)O)E

The correct answer is E.Explanation:The given chemical reaction sequence is as follows: In this reaction sequence, the compound (acetylene) reacts with sodium hydride (NaHI) to form compound A. Compound A then reacts with methyl iodide (CH3I) at a low temperature (-272°C) to form compound B. Compound B reacts with sodium amide (NaNH2) at a low temperature (-272°C) to form compound C. Compound C then reacts with methyl iodide (CH3I) to form compound D. Finally, compound D reacts with water (H2O) to form compound E.Therefore, the correct answer is E.