List of top Questions asked in CBSE CLASS XII

Which of the following ligands forms a chelate complex?
When MnO\(_2\) is fused with KOH in air, it gives:
The formation of cyanohydrin from an aldehyde is an example of:
The correct order of the ease of dehydration of the following alcohols by the action of conc. H2SO4 is:
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.
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.
Acetic acid reacts with PCl5to give:
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.
The reaction of an alkyl halide with sodium alkoxide forming ether is known as:
For an electrolyte undergoing association in a solvent, the van’t Hoff factor:
Which functional groups of glucose interact to form cyclic hemiacetal leading to pyranose structure?
In the Arrhenius equation, when log k is plotted against 1/T, a straight line is obtained whose:
Calculate the potential of Iron electrode in which the concentration of Fe2+ ion is 0.01 M. Given \( E^{\circ}_{\text{Fe}^{2+}/\text{Fe}} = -0.45 \, \text{V at 298 K} \)
[Given: log 10 = 1]
When a certain conductivity cell was filled with 0.05 M KCl solution, it has a resistance of 100 ohms at 25°C. When the same cell was filled with 0.02 M AgNO3 solution, the resistance was 90 ohms. Calculate the conductivity and molar conductivity of $\text{AgNO}_{3}$ solution.
Given: Conductivity of 0.05 M KCl solution = \( 1.35 \times 10^{-2} \, \Omega^{-1} \, \text{cm}^{-1} \)
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?