To solve this problem, we need to understand the reaction between nitrogen $(N_2)$ and calcium carbide $(CaC_2). \newline$The reaction is as follows:$\newline$When nitrogen gas is passed over calcium carbide at high temperatures, the following reaction occurs:$\newline CaC_2 + N_2 \rightarrow CaCN_2 + C \newline$Explanation:$\newline$• Calcium carbide $(CaC_2)$ reacts with nitrogen $(N_2)$ to form calcium cyanamide $(CaCN_2)$ and carbon $(C). \newline$• This reaction is used industrially to produce calcium cyanamide, which is a nitrogen fertilizer.$\newline$Analyzing the options:$\newline$• Option 1: Ca(CN)_2 is incorrect because calcium cyanamide is not formed as a dicyanide.$\newline$• Option 2: CaCN is incorrect because calcium cyanide is not the product.$\newline$• Option 3: CaCN_2 is correct because calcium cyanamide is the product.$\newline$• Option 4: Ca_2CN is incorrect because this compound does not form in the reaction.$\newline$Therefore, the correct option is Option 3: CaCN_2.