Inorganic Chemistry is often the “make or break” section of the JEE Main. Why? Because while everyone remembers the trends, the top scorers remember the exceptions. Whether it’s the peculiar screening effect in transition elements or the unexpected bond angles in p-block hydrides, these anomalies are the favorite hunting grounds for NTA paper setters.
To help you move beyond rote memorization, we’ve compiled a definitive quiz on the most frequent exceptions encountered in the syllabus.
Why do these exceptions exist?
Most “exceptions” in inorganic chemistry aren’t random; they are usually governed by:
- Relativistic effects (heavy elements).
- Poor shielding of d and f orbitals (Lanthanoid Contraction).
- Half-filled and fully-filled electronic configurations.
The Ultimate Inorganic Exception Quiz (20 Questions)
1. Which element has a higher electron gain enthalpy than Fluorine?
- (a) Iodine
- (b) Bromine
- (c) Chlorine
- (d) Nitrogen
- Answer: (c) Chlorine (Due to the small size of F, inter-electronic repulsions are higher).
2. The expected order of Ionization Enthalpy is $B > Al > Ga$. What is the actual order?
- (a) $B > Ga > Al$
- (b) $Ga > B > Al$
- (c) $Al > Ga > B$
- (d) $B > Al > Ga$
- Answer: (a) $B > Ga > Al$ (Due to poor shielding of 10 d-electrons in Ga).
3. Which of the following does not follow the Octet Rule?
- (a) $CH_4$
- (b) $CO_2$
- (c) $NO$
- (d) $H_2O$
- Answer: (c) $NO$ (It is an odd-electron molecule).
4. Why is the boiling point of $NH_3$ higher than $PH_3$?
- (a) Van der Waals forces
- (b) Hydrogen bonding
- (c) Metallic bonding
- (d) Ionic character
- Answer: (b) Hydrogen bonding.
5. Which has the highest melting point among Group 14 elements?
- (a) Carbon
- (b) Silicon
- (c) Germanium
- (d) Tin
- Answer: (a) Carbon (Diamond has a very strong 3D network).
6. The bond angle in $H_2O$ is $104.5^\circ$. What is the approximate bond angle in $H_2S$?
- (a) $109^\circ$
- (b) $107^\circ$
- (c) $92^\circ$
- (d) $120^\circ$
- Answer: (c) $92^\circ$ (Drago’s Rule: No hybridization in $H_2S$).
7. Which of these is an amphoteric oxide?
- (a) $Na_2O$
- (b) $SO_3$
- (c) $Al_2O_3$
- (d) $CaO$
- Answer: (c) $Al_2O_3$.
8. In the preparation of $XeF_2$, which gas acts as an oxidizing agent?
- (a) $O_2$
- (b) $PtF_6$
- (c) $F_2$
- (d) $He$
- Answer: (b) $PtF_6$ (Neil Bartlett’s famous discovery).
9. Which of the following transition elements has the highest melting point?
- (a) $Fe$
- (b) $Cr$
- (c) $W$ (Tungsten)
- (d) $Hg$
- Answer: (c) $W$ (Maximum number of unpaired electrons for metallic bonding).
10. What is the basicity of $H_3PO_3$?
- (a) 1
- (b) 2
- (c) 3
- (d) 4
- Answer: (b) 2 (It contains only two replaceable P-OH hydrogens).
11. Which alkali metal bicarbonate exists as a solid?
- (a) $LiHCO_3$
- (b) $NaHCO_3$
- (c) All of them
- (d) None
- Answer: (b) $NaHCO_3$ ($LiHCO_3$ exists only in solution).
12. The $+1$ oxidation state is more stable than $+3$ for which element?
- (a) $Al$
- (b) $Ga$
- (c) $In$
- (d) $Tl$
- Answer: (d) $Tl$ (Inert Pair Effect).
13. Which gas is evolved when Copper reacts with dilute $HNO_3$?
- (a) $NO_2$
- (b) $NO$
- (c) $N_2O$
- (d) $H_2$
- Answer: (b) $NO$.
14. Lead ($Pb$) mostly forms $Pb^{2+}$ compounds instead of $Pb^{4+}$ because of:
- (a) Shielding effect
- (b) Inert pair effect
- (c) Electronegativity
- (d) Atomic radius
- Answer: (b) Inert pair effect.
15. Which of these is the strongest reducing agent in aqueous solution?
- (a) $Li$
- (b) $Na$
- (c) $K$
- (d) $Cs$
- Answer: (a) $Li$ (High hydration enthalpy).
16. Phosphorus has several allotropes. Which is the most stable?
- (a) White P
- (b) Red P
- (c) Black P
- (d) Yellow P
- Answer: (c) Black P.
17. The shape of $XeF_4$ is:
- (a) Tetrahedral
- (b) Square Planar
- (c) See-saw
- (d) Octahedral
- Answer: (b) Square Planar.
18. Which halide of Silver is insoluble in water?
- (a) $AgF$
- (b) $AgCl$
- (c) $AgBr$
- (d) Both (b) and (c)
- Answer: (d) Both (b) and (c). ($AgF$ is uniquely soluble).
19. In the chromyl chloride test, the red vapors are of:
- (a) $CrCl_3$
- (b) $CrO_2Cl_2$
- (c) $K_2CrO_4$
- (d) $Cr_2O_3$
- Answer: (b) $CrO_2Cl_2$.
20. Boranes are known as:
- (a) Electron-rich compounds
- (b) Electron-precise compounds
- (c) Electron-deficient compounds
- (d) Ionic compounds
- Answer: (c) Electron-deficient compounds.