Final answer:
The correct formula for iron (I) cyanide should be Fe(CN)2, which reflects the 1:2 ratio of ferrous ions to cyanide ions. None of the given options are correct, but option (d) is the closest to a feasible chemical formula.
Step-by-step explanation:
The correct formula for iron (I) cyanide is 'FeCN'. Iron (I), also known as ferrous ion, is Fe²⁻, and the cyanide ion is CN⁻. To write the formula for the compound, we combine the cation and anion in a ratio that results in a neutral compound. Each Fe²+ ion pairs with two CN⁻ ions to maintain charge neutrality, making the empirical formula Fe(CN)₂. However, this is not one of the options provided, which suggests a possible error in the question. Among the provided options, the closest incorrect answer is (d) 'Fe2CN3' because it suggests a 2:3 ratio of iron to cyanide, but the correct stoichiometry should be a 1:2 ratio, reflecting one ferrous ion for every two cyanide ions.