List of top Questions asked in CBSE CLASS XII

Predict whether Van’t Hoff factor will be less or greater than one when Ethanoic acid is dissolved in benzene.
Define ideal solution.
Calculate the mass of CaCl$_2$ (molar mass = 111 g mol$^{-1}$) to be dissolved in 500 g of water to lower its freezing point by 2K, assuming that CaCl$_2$ undergoes complete dissociation.
What is Hinsberg’s reagent?
Why Zinc is not regarded as a transition element?
What is Lanthanoid contraction?
Why is first ionization enthalpy of chromium lower than that of Zn?
Why are transition elements good catalysts?
What happens when ethyl chloride is treated with alcoholic potassium hydroxide?
Show that the time required for 99.9% completion in a first-order reaction is 10 times of half-life (t$_{1/2}$) of the reaction.
Predict whether \([CoF_6]^{3-}\) is diamagnetic or paramagnetic and why?
\([Atomic \ \ number : Co = 27]\)
What is meant by a unidentate ligand? Give an example.
Calculate emf of the following cell at 25°C:
Sn/Sn$^{2+}$(0.001 M) || H$^+$(0.01 M) | H$_2$(g)(1 bar) | Pt(s)
Given: E°(Sn$^{2+}$/Sn) = -0.14 V, E° H$^+$/H$_2$ = 0.00 V (log 10 = 1)
Write chemical equations for the following reactions:
(a) Hydroboration – Oxidation reaction:
(b) Williamson Synthesis:
(c) Friedel-Crafts Alkylation of Anisole:
(d) Reimer-Tiemann Reaction:
Give chemical tests to distinguish between the following pairs of compounds:
(i) Phenol and Benzoic acid:
(ii) Propanal and Propanone:
Which one of the given compounds is a stronger acid and why?
CH$_2$FCH$_2$COOH or CH$_3$CHFCH$_2$COOH
Explain the following terms:
(a) Essential amino acids:
(b) Peptide bond:
(c) Denaturation:
Write the IUPAC name of the given compound:
3– Bromo– 1 chlorocyclohexene
The presence of –NO$_2$ group at ortho or para position increases the reactivity of haloarenes towards nucleophilic substitution reactions. Give reason to explain the above statement.
18 g of a non-volatile solute is dissolved in 200 g of H$_2$O, and it freezes at 272.07 K. Calculate the molecular mass of the solute (K$_f$ for water = 1.86 K kg mol$^{-1}$).
Which compound in the given pair will undergo S$_N$2 reaction at a faster rate and why?
CH$_3$–CH$_2$–I and CH$_3$–CH$_2$–Br
Arrange the following compounds in the increasing order of their boiling points:
Butane, 1-Bromobutane, 1-Iodobutane, 1-Chlorobutane
How will you convert the following?
(i) Toluene to Benzoic acid:
(ii) Ethanol to 3-Hydroxybutanal:
What happens when glucose reacts with bromine water? Write the chemical equation.
Write the electronic configuration for d$^4$ ion if \( \Delta_0 < P \) on the basis of crystal field theory.