Hydrogen s-Block and p-Block Elements formulas for JEE Main & Advanced

Water Gas Shift Reaction

When to use. When solving problems on industrial hydrogen production or thermochemical cycles.

Trap. The catalyst is usually iron oxide or chromium oxide, not just any metal.

Hardness of Water Removal

When to use. When solving water treatment problems or distinguishing between hardness types.

Trap. Boiling only removes temporary hardness, not permanent.

Reaction of Alkali Metals with Water

When to use. When writing equations for alkali metal reactions or predicting products.

Trap. Lithium does not produce a flame; sodium produces a yellow flame; potassium produces a lilac flame.

Thermal Decomposition of Carbonates

When to use. When predicting products of heating metal carbonates or comparing thermal stability.

Trap. BeCO₃ is unstable and decomposes at ~100°C, while BaCO₃ requires >1000°C.

Preparation of Borax (Na₂B₄O₇·10H₂O)

When to use. When writing industrial preparation of boron compounds or in qualitative analysis.

Trap. The product is not pure borax; sodium metaborate (NaBO₂) is a byproduct.

Silicones

When to use. When discussing polymer chemistry or applications of silicon compounds.

Trap. Silicones are not based on carbon; they have Si-O bonds, not C-C.

Reaction of Silicon with Alkali

When to use. When writing reactions of silicon or comparing with carbon (which does not react with alkali).

Trap. Silicon does not react with acids (except HF), but reacts with alkalis.

Borax Bead Test

When to use. When identifying metal ions in qualitative analysis.

Trap. The bead is tested in both oxidizing and reducing flames, and colours depend on the flame (e.g. Fe: yellow-brown oxidizing, green reducing).

Reaction of Ammonia with Chlorine

When to use. When predicting products of ammonia reactions or in industrial chemistry.

Trap. NCl₃ is explosive, not stable.

Ostwald's Process for HNO₃

When to use. When solving industrial chemistry problems or writing the process steps.

Trap. The catalyst is Pt/Rh, not just platinum.

Sulfuric Acid: Contact Process

Trap. SO₃ is not absorbed in water directly (forms a mist); it is absorbed in H₂SO₄.

Reaction of Halogens with Water

When to use. When writing reactions of halogens or comparing their oxidizing power.

Trap. Fluorine gives O₂, not HOCl, due to high oxidizing power.

Interhalogen Compounds

When to use. When predicting structures or reactions of halogen compounds.

Trap. The central atom is always the larger halogen (lower electronegativity).