This chapter covers the unique position of hydrogen in the periodic table, the structure of water, and the chemical properties of hydrides. It is a high-yield topic because it bridges inorganic chemistry trends with practical applications in fuel cells and environmental water treatment.
JEE Main 2027 Engineering Focus: High-Yield Problem Solving & Negative Marking Defense
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- Timed Shift PYQ Practice: Solve at least 15-20 recent shift questions (2021-2026) under a strict 2.5-minute timer per numerical/MCQ.
1. 📚 Quick Revision Notes & Core Theory
- Water Gas Shift Reaction: CO(g) + H2O(g) → CO2(g) + H2(g) (Used for the industrial production of dihydrogen).
- Auto-protolysis of Water: H2O(l) + H2O(l) ⇌ H3O+(aq) + OH-(aq) (Represents the amphoteric nature of water acting as both an acid and a base).
3. 📝 Interactive Chapter DPP & Practice Questions
💡 View Step-by-Step Solution & Answer Key
Correct Answer: (b)
Explanation: $\mathrm{C}, \mathrm{Si}, \mathrm{Ge}$ form electron precise hydrides. Electron precise hydrides are compounds where total number of valence electrons is exactly enough to form covalent bonds between all the atoms in the molecules resulting in forming a complete octet.
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Correct Answer: (b)
Explanation: Water-gas is a mixture of $\mathrm{CO}_{(\mathrm{g})}$ and hydrogen. It is formed by the following reaction. $\underset{\begin{array}{c}\text { Methane } \\ \text { (Hydrocarbon) }\end{array}}{\mathrm{CH}_{4(\mathrm{~g})}}+\underset{\text { Steam }}{\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}} \xrightarrow{1270 \mathrm{~K}} \underbrace{\mathrm{CO}_{(\mathrm{g})}+3 \mathrm{H}_{2(\mathrm{~g})}}_{\text {Water-gas (syngas) }}$
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Correct Answer: (c)
Explanation: The most effective water softening method is ion exchange process because in this method the dissolved calcium and magnesium ions that cause hardness of water are removed easily with the help of an ion exchange process. Also, in this method relatively large number of calcium and magnesium ions displace smaller sodium ions. This method is cheaper method and the chemicals used in it are safe to work with and easy to handle.
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Correct Answer: (b)
Explanation: Lithium imide is an inorganic compound with the chemical formula $\mathrm{Li}_2 \mathrm{NH}$. This white solid can be formed by a reaction between lithium amide and lithium hydride. $\mathrm{LiH}_2+\mathrm{LiH} \longrightarrow \underset{\text { Lithium imide }}{\mathrm{Li}_2 \mathrm{NH}+\mathrm{H}_2}$ The product is light sensitive and can undergo disproportionation to form lithium nitride.
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Correct Answer: (c)
Explanation: The reaction and their products are $ \begin{aligned} & 2 \mathrm{NaBH}_4+\mathrm{I}_2 \xrightarrow{\Delta} \mathrm{~B}_2 \mathrm{H}_6+2 \mathrm{NaI}+\mathrm{H}_2 \uparrow \\ & 2 \mathrm{BF}_3+6 \mathrm{NaH} \xrightarrow{\Delta} \mathrm{~B}_2 \mathrm{H}_6+6 \mathrm{NaF} \\ & 4 \mathrm{BF}_3+3 \mathrm{LiAlH}_4 \xrightarrow{ } 2 \mathrm{~B}_2 \mathrm{H}_6+3 \mathrm{Li}\left[\mathrm{AlF}_4\right] \\ & 3 \mathrm{~B}_2 \mathrm{H}_6+6 \mathrm{NH}_3 \xrightarrow{\Delta} 2 \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6+12 \mathrm{H}_2 \uparrow \end{aligned} $ Hence, reaction given in (I) and (IV) give hydrogen as one product.
4. ❓ Frequently Asked Questions (Exam Strategy)
❓ How many questions appear from JEE Main Chemistry: Hydrogen And Its Compounds High-Yield Practice Questions, Formulas & PYQ Breakdown (2026-27) in JEE Main Session 1?
❓ What is the best approach to avoid negative marks in JEE Main Chemistry: Hydrogen And Its Compounds High-Yield Practice Questions, Formulas & PYQ Breakdown (2026-27)?
❓ Why is dihydrogen called a 'fuel of the future'?
❓ What is the difference between temporary and permanent hardness of water?
❓ Does hydrogen form ionic bonds?
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