`Ag_(2)S+NaCNrarrAoverset(Zn)rarrB`, Hence A and B are -

Options

A. `Na_(2)[Zn(CN)_(4], Zn`
B. `Na[Ag(CN)_(2)], Ag`
C. `Na_(2)[Ag(CN)_(4)], Ag`
D. `Na_(2)[Ag(CN)_(4)], Ag`

Answer

To solve the question regarding the reactions of silver sulfide (Ag₂S) with sodium cyanide (NaCN) and zinc (Zn), we will break down the reactions step by step.

### Step 1: Reaction of Ag₂S with NaCN
When silver sulfide (Ag₂S) reacts with sodium cyanide (NaCN), it forms a complex ion. The reaction can be represented as follows:

\[ \text{Ag}_2\text{S} + 4 \text{NaCN} \rightarrow 2 \text{Na}[\text{Ag(CN)}_2] + \text{Na}_2\text{S} \]

Here, the silver ions (Ag⁺) from silver sulfide react with cyanide ions (CN⁻) to form a complex ion, specifically the dicyanoargentate complex \([\text{Ag(CN)}_2]^-\).

### Step 2: Identify Compound A
From the reaction above, we see that the product formed is the complex ion \([\text{Ag(CN)}_2]^-\) along with sodium sulfide (Na₂S). Therefore, the compound A is:

\[ \text{A} = \text{Na}_2[\text{Ag(CN)}_2] \]

### Step 3: Reaction of Ag₂S with Zinc (Zn)
Next, when silver sulfide (Ag₂S) reacts with zinc (Zn), the zinc reduces the silver ions while being oxidized itself. The reaction can be represented as follows:

\[ \text{Ag}_2\text{S} + \text{Zn} \rightarrow 2 \text{Ag} + \text{ZnS} \]

In this reaction, zinc displaces silver from silver sulfide, resulting in the formation of elemental silver (Ag) and zinc sulfide (ZnS).

### Step 4: Identify Compound B
From the reaction above, we see that the products formed are elemental silver and zinc sulfide. Therefore, the compound B is:

\[ \text{B} = \text{ZnS} \]

### Final Answer
Thus, the compounds A and B are:
- A = Na₂[Ag(CN)₂]
- B = ZnS