JEE Advanced Inorganic Chemistry Flashcards

24 sample cards from the Inorganic Chemistry deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Why does nitrogen exist as N2 with a triple bond while phosphorus exists as P4?

   Nitrogen's small 2p orbitals overlap effectively to form a strong N≡N triple bond; phosphorus's larger 3p orbitals form weak pπ–pπ bonds, so it forms single-bonded P4 tetrahedra instead.

2. Arrange the hydrides of Group 15 (NH3 to BiH3) in order of basicity and thermal stability.

   Basicity and thermal stability both decrease down the group: NH3 > PH3 > AsH3 > SbH3 > BiH3.

3. Describe the structures of the two main oxides of sulfur, SO2 and SO3 (gas phase).

   SO2 is bent/angular (sp2, one lone pair on S); gaseous SO3 is trigonal planar (sp2, no lone pair on S).

4. Why does the acidic strength of hydrohalic acids increase HF < HCl < HBr < HI?

   Down the group bond strength (H–X) decreases, so the H–X bond dissociates more easily, increasing acid strength; HI is the strongest.

5. What is the bleaching action of chlorine and SO2 — and how do they differ?

   Chlorine bleaches by oxidation (permanent, due to nascent oxygen from Cl2 + H2O → HCl + [O]); SO2 bleaches by reduction (temporary, color returns on exposure to air).

6. Why are noble gases (Group 18) chemically inert, and which is most reactive?

   They have completely filled valence shells (ns2 np6) and very high ionization enthalpies. Xenon is the most reactive (forms compounds like XeF2, XeF4, XeF6) due to lower ionization energy.

7. Give the shapes of XeF2, XeF4, and XeF6 using VSEPR.

   XeF2: linear (3 lone pairs, sp3d); XeF4: square planar (2 lone pairs, sp3d2); XeF6: distorted octahedral (1 lone pair, sp3d3).

8. Why do transition metals show variable oxidation states?

   Because the (n−1)d and ns orbitals have similar, low energy, so electrons from both subshells can participate in bonding, allowing multiple oxidation states.

9. Why are many transition metal compounds coloured?

   Due to d–d electronic transitions: an electron absorbs visible light to move between split d-orbitals (energy gap Δ), and the complementary colour is transmitted/observed.

10. Why do transition metals and their ions often act as good catalysts?

    They provide variable oxidation states (allowing electron transfer) and surfaces/partially filled d-orbitals that adsorb reactants and form intermediates of suitable energy.

11. Why is the melting point of Mn lower than that of its neighbours Cr and Fe?

    Mn's half-filled stable 3d5 4s2 configuration results in fewer electrons available for metallic bonding, lowering metallic bond strength and melting point.

12. What causes the magnetic moment of a transition metal ion, and give the spin-only formula.

    Unpaired d-electrons. Spin-only magnetic moment μ = √[n(n+2)] BM, where n is the number of unpaired electrons.

13. State Werner's coordination theory in terms of primary and secondary valencies.

    Primary valency = oxidation state, satisfied by negative ions, ionizable. Secondary valency = coordination number, satisfied by ligands, non-ionizable and directional (fixes geometry).

14. Define ligand, denticity, and give an example of a bidentate and an ambidentate ligand.

    A ligand is an ion/molecule that donates an electron pair to a metal. Denticity = number of donor atoms. Bidentate example: ethylenediamine (en) or oxalate; ambidentate example: NO2− (N or O) or SCN− (S or N).

15. According to Crystal Field Theory, how do d-orbitals split in an octahedral field?

    They split into a lower triply degenerate t2g set (dxy, dyz, dxz) and a higher doubly degenerate eg set (dz2, dx2−y2), separated by the crystal field splitting energy Δo.

16. What determines whether an octahedral complex is high-spin or low-spin?

    The relative size of Δo and pairing energy P. If Δo > P (strong-field ligand) → low-spin; if Δo < P (weak-field ligand) → high-spin.

17. Give the spectrochemical series ordering for a few key ligands from weak to strong field.

    I− < Br− < Cl− < F− < OH− < H2O < NH3 < en < NO2− < CN− < CO (weak field → strong field).

18. Name the complex [Co(NH3)6]Cl3 and give the metal's oxidation state and coordination number.

    Hexaamminecobalt(III) chloride; Co oxidation state = +3; coordination number = 6.

19. What is the deep blue colour seen in the borax bead test or copper sulfate, and what does cupric ion form with excess ammonia?

    Cu2+ with excess ammonia forms the deep blue tetraamminecopper(II) ion, [Cu(NH3)4]2+. (CuSO4·5H2O is blue due to hydrated Cu2+.)

20. What is the action of acidified KMnO4 as an oxidizing agent (half reaction)?

    In acidic medium: MnO4− + 8H+ + 5e− → Mn2+ + 4H2O (purple MnO4− reduced to colourless Mn2+); it is a strong oxidant.

21. What is the colour change and product when K2Cr2O7 acts as an oxidizing agent in acidic medium?

    Orange Cr2O7^2− + 14H+ + 6e− → 2Cr3+ + 7H2O; dichromate (orange) is reduced to green Cr3+.

22. Define calcination and roasting in metallurgy.

    Calcination: heating an ore (usually carbonate/hydroxide) in limited/absence of air to remove volatile matter and form oxide. Roasting: heating a sulfide ore in excess air to convert it to oxide (and release SO2).

23. In the metallurgy of iron in a blast furnace, what is the role of limestone (CaCO3)?

    It decomposes to CaO, which acts as a flux combining with silica (SiO2) gangue to form calcium silicate slag (CaSiO3), removing impurities.

24. In qualitative salt analysis, which group reagent precipitates Group II cations and which precipitates Group III cations?

    Group II: H2S in presence of dilute HCl (acidic medium) precipitates sulfides (e.g., Cu, Pb, Cd). Group III: NH4Cl + NH4OH precipitates hydroxides (e.g., Al, Fe, Cr).

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