List of top Questions asked in CBSE CLASS XII

Which of the following is most acidic?
Anisole reacts with HI to give:
When MnO\(_2\) is fused with KOH in air, it gives:
For an electrolyte undergoing association in a solvent, the van’t Hoff factor:
Acetic acid reacts with PCl5to give:
The formation of cyanohydrin from an aldehyde is an example of:
In the Arrhenius equation, when log k is plotted against 1/T, a straight line is obtained whose:
The reaction of an alkyl halide with sodium alkoxide forming ether is known as:
The correct order of the ease of dehydration of the following alcohols by the action of conc. H2SO4 is:
Which functional groups of glucose interact to form cyclic hemiacetal leading to pyranose structure?
Assertion (A): When NaCl is added to water, a depression in freezing point is observed.
Reason (R): NaCl undergoes dissociation in water.
Assertion (A): Separation of Zr and Hf is difficult.
Reason (R): Zr and Hf have similar radii due to lanthanoid contraction.
Assertion (A): The pKa} of ethanoic acid is lower than that of C1} – CH2} – COOH.
Reason (R): Chlorine shows electron withdrawing (–I) effect which increases the acidic character of C1} – CH2} – COOH.
Assertion (A): Aniline is a stronger base than ammonia.
Reason (R): The unshared electron pair on nitrogen atom in aniline becomes less available for protonation due to resonance.
Which of the following is an allylic halide?
allylic halide
Which isomer of \(C_4H_9Cl\) has the lowest boiling point?
Write the main product in each of the following reactions: 
oxidation of the hydroboration product
(a) What is peptide linkage?
(b) What type of bonds hold a DNA double helix together?
(c) Which one of the following is a polysaccharide?
(d) Give one example each for water-soluble vitamins and fat-soluble vitamins.
Give reason for the violet colour of the complex \( [\text{Ti(H}_2\text{O)} _6]^{3+} \) on the basis of crystal field theory.
\( [\text{Cr(NH}_3) _6]^{3+} \) is paramagnetic while \( [\text{Ni(CN)}_4]^{2-} \) is diamagnetic. Explain why.
Explain why \( [\text{Fe(CN)}_6]^{3-} \) is an inner orbital complex, whereas \( [\text{Fe(H}_2\text{O)}_6]^{3+} \) is an outer orbital complex.
At the same temperature, \( CO_2 \) gas is more soluble in water than \( O_2 \) gas. Which one of them will have a higher value of \( K_H \) and why?
N,N-diethylbenzenesulphonamide is insoluble in alkali. Give reason.
Aniline does not undergo Friedel-Crafts reaction. Why?
\( E^0 \) value of Cu\(^{2+}\)/Cu is \( +0.34 \) V.