Q.Match the catalysts given in Column I with the processes given in Column II.
Column I (Catalyst):

The key idea is recognising each catalyst's specific industrial reaction — matching industrial catalysts to the processes they enable.

Step 1 – Identify each catalyst’s role:

• (i) Ni/H₂ is used for hydrogenation of vegetable oils to ghee.
• (ii) Cu₂Cl₂ is a catalyst in the Sandmeyer reaction (conversion of diazonium salts to aryl chlorides).
• (iii) V₂O₅ is the catalyst in the Contact process for H₂SO₄ manufacture.
• (iv) Finely divided iron is the catalyst in Haber’s process for NH₃ synthesis. …

The key to solving this is not memorising a list, but understanding what each catalyst does in its reaction. A catalyst lowers the activation energy for a specific transformation — so if you know the transformation, you know the catalyst.

Let’s walk through each catalyst one by one.

1. Ni in the presence of hydrogen — This is the classic condition for the hydrogenation of unsaturated fats. Vegetable oils (which contain carbon-carbon double bonds) are treated with hydrogen gas over a nickel catalyst to produce semi-solid fats like ghee or margarine. So (i) matches with (c) Vegetable oil to ghee.

2. $Cu_2Cl_2$ — Cuprous chloride is used in the Sandmeyer reaction, where a diazonium salt is converted to an aryl chloride. The copper(I) chloride acts as a catalyst that facilitates the replacement of the diazonium group ($-N_2^+$) with a chlorine atom. So (ii) matches with (d) Sandmeyer reaction.

3. $V_2O_5$ — Vanadium pentoxide is the catalyst for the Contact process, which manufactures sulfuric acid. In this process, $SO_2$ is oxidised to $SO_3$ in the presence of $V_2O_5$ as the catalyst. So (iii) matches with (b) Contact process.

4. Finely divided iron — This is the catalyst used in the Haber’s process for the synthesis of ammonia from nitrogen and hydrogen. Iron (often promoted with oxides of potassium and aluminium) provides the surface for the reaction $N_2 + 3H_2 \rightleftharpoons 2NH_3$. So (iv) matches with (e) Haber's Process. …

Concept: Industrial Catalysts and Their Applications

This is a matching question based on catalyst–process association — a common topic in inorganic and industrial chemistry for Indian exams (JEE, NEET, Boards).

Method: Process–Catalyst Recall & Elimination

Step 1: Identify the most famous catalyst–process pairs first.

• Ziegler–Natta catalyst → used for polymerisation of alkenes (e.g., polyethylene).

  Given in Column I: $TiCl_4 + Al(CH_3)_3$ → matches (a).

• Contact process → manufacture of $H_2SO_4$ uses $V_2O_5$ as catalyst.

  So (iii) matches (b).

• Haber's process → synthesis of $NH_3$ uses finely divided iron with promoters.

  So (iv) matches (e).

Step 2: Match the remaining using specific reactions.

• Vegetable oil to ghee → hydrogenation of unsaturated fats.

  Catalyst: Ni in presence of hydrogen.

  So (i) matches (c).

• Sandmeyer reaction → conversion of diazonium salts to aryl halides using $Cu_2Cl_2$ (or $CuBr$, $CuCN$).

  So (ii) matches (d). …

Here are the common mistakes students make when matching catalysts to processes, along with how to avoid each.

1. Confusing "Ni in presence of hydrogen" with the Haber Process

• The Mistake: Students often associate nickel (Ni) with the Haber process (ammonia synthesis) because both involve hydrogen gas. They forget that the Haber process uses iron, not nickel.
• How to Avoid: Memorize the specific catalyst for each industrial process.
  • Haber process: Finely divided iron ($Fe$) with promoters ($K_2O$, $Al_2O_3$).
  • Hydrogenation of oils (ghee): Nickel ($Ni$) in the presence of $H_2$.
  • Key trick: "Nickel makes it nice and solid (ghee)."

2. Mixing up $V_2O_5$ with the Decomposition of $KClO_3$

• The Mistake: Students see a transition metal oxide ($V_2O_5$) and assume it is a general catalyst for decomposition reactions (like $MnO_2$ for $KClO_3$).
• How to Avoid: Remember the specific reaction for each oxide.
  • $V_2O_5$ is the catalyst for the Contact process (making $H_2SO_4$ from $SO_2$ to $SO_3$).
  • $MnO_2$ (not listed here) is the common catalyst for $KClO_3$ decomposition.
  • Mnemonic: "Vanadium Vital for Vitriol (sulfuric acid)."

3. Forgetting the Role of $Cu_2Cl_2$ in the Sandmeyer Reaction

• The Mistake: Students confuse $Cu_2Cl_2$ (cuprous chloride) with a catalyst for oxidation or reduction, or they think it is used in the Haber process.
• How to Avoid: Link copper(I) chloride directly to diazonium salt chemistry.
  • Sandmeyer reaction: Replaces a diazonium group ($-N_2^+$) with a halogen ($Cl$, $Br$, $CN$) using $Cu_2Cl_2$ or $Cu_2Br_2$.
  • Mnemonic: "Copper Chloride for Chlorination (Sandmeyer)."

4. Misidentifying the Ziegler-Natta Catalyst

• The Mistake: Students think "Ziegler-Natta" is a single compound, so they match it with a simple metal like $Ni$ or $Fe$.
• How to Avoid: Recognize that the Ziegler-Natta catalyst is a combination of a transition metal halide and an organoaluminum compound.
  • The correct pair is $TiCl_4 + Al(CH_3)_3$ (Titanium tetrachloride + Trimethylaluminum).
  • Key clue: Look for the two components in the list — only one option has a "+" sign. …