Q.When ethyl iodide is treated with dry silver oxide it forms :

Two molecules of ethyl iodide react with dry $Ag_2O$ to give diethyl ether, with $AgI$ as the by-product.

Dry silver oxide is a classical reagent for converting alkyl halides into ethers: $2C_2H_5I + Ag_2O \rightarrow (C_2H_5)_2O + 2AgI$. Mechanistically, the oxide oxygen of $Ag_2O$ displaces iodide from one ethyl iodide molecule (assisted by the strong affinity of $Ag^+$ for $I^-$, which drives the reaction), generating an intermediate silver ethoxide/alkoxide species that then reacts with a second molecule of ethyl iodide in a Williamson-type $S_N2$ step, giving the symmetrical ether $C_2H_5-O-C_2H_5$. Option (d), silver ethoxide, is only the transient intermediate, not the isolated pro …