Which of the following are correct processes ?

Options

A. `Fe + Al_(2) O_(3) rarr 2Al + Fe_(2) O_(3)`
B. `ZnO + C rarr Zn + CO`
C. `Cr_(2)O_(3) + 2 Al rarr 2Cr + Al_(2) O_(3)`
D. `2[Ag(CN)_(2)]^(Ө) + Zn rarr 2Ag +[Zn(CN)_(4)]^(2-)`.

Answer

To determine which of the given processes are correct, we will analyze each process step by step.

### Step 1: Analyze the first process - Iron reacting with Alumina
- The first process states that iron can displace aluminum from alumina (Al₂O₃) to form iron oxide.
- However, this is incorrect because iron is less reactive than aluminum. In the reactivity series of metals, aluminum is placed above iron, meaning aluminum cannot be displaced by iron.
- **Conclusion:** This process does not occur.

### Step 2: Analyze the second process - Reduction of Zinc Oxide
- The second process involves the reduction of zinc oxide (ZnO) using coke (carbon) as a reducing agent.
- The reaction can be represented as:
\[ \text{ZnO} + \text{C} \xrightarrow{\text{heat}} \text{Zn} + \text{CO} \]
- This process is indeed correct as it successfully reduces zinc oxide to zinc metal and produces carbon monoxide.
- **Conclusion:** This process occurs.

### Step 3: Analyze the third process - Thermite Reaction
- The third process describes the thermite reaction, where aluminum reacts with chromium oxide (Cr₂O₃).
- The reaction can be represented as:
\[ \text{Al} + \text{Cr}_2\text{O}_3 \rightarrow \text{Al}_2\text{O}_3 + 2\text{Cr} \]
- In this reaction, aluminum displaces chromium from its oxide due to its higher reactivity. This is a well-known reaction used for welding and producing chromium.
- **Conclusion:** This process occurs.

### Step 4: Analyze the fourth process - Leaching of Silver
- The fourth process involves the leaching of silver, which typically refers to the process of extracting silver from its ore using a solvent.
- In this process, silver ions are dissolved and can later be precipitated out, often using a chemical like sodium chloride (NaCl) to form silver chloride (AgCl).
- This is a valid metallurgical process used for the extraction of silver.
- **Conclusion:** This process occurs.

### Final Conclusion
- The correct processes among the given options are:
- **Option 2:** Reduction of Zinc Oxide
- **Option 3:** Thermite Reaction
- **Option 4:** Leaching of Silver
- **Incorrect Process:** Option 1 (Iron reacting with Alumina)

### Summary of Correct Processes
- **Correct Processes:** 2, 3, and 4
- **Incorrect Process:** 1