Question

What is the Roman numeral that should be used in the following: silver (_______) sulfide? A. No Roman numeral should be used here. B. I C. III D. II

Answer 1

The answer is I

The correct way of writing this would be silver(I) sulfide, but silver sulfide without the (I) is also OK because it isn't always writte, nor is it necessary to write the (I). 
 

Answer 2

Answer: The correct answer is Option B.

Explanation: The compound given to us is $Ag_2S$. To write the IUPAC name for this compound, we need to follow some rules:

1. First write the name of the cation with its oxidation state in roman numbers.

2. Then write the name of the anion which may be a polyatomic ion or a non-metal.

3. The anion is used with a suffix '-ide'. Example: For chlorine, the anion would be named as chloride, for sulfur, the anion would be sulfide.

For the given compound, 2 silver atoms are needed to neutralize the charge on 1 sulfur atom.

Hence, the oxidation number of silver atom is '1'. So, the IUPAC name for the compound will be silver (I) sulfide.

Therefore, the correct option is B.