List of top Questions asked in CBSE CLASS XII- 2026

The boiling points of the alkyl halides with the same alkyl group decrease in the given order: $RI \gt RBr \gt RCl \gt RF$. Explain the above statement.
Why is chemistry of actinoids complicated as compared to lanthanoids?
Write the IUPAC name of the given compound: $CH_3CH(CH_3)CH(Br)CH_3$

Rate constant k for the first order reaction is $2.54 \times 10^{-3} s^{-1}$. Calculate the time required for three-fourth of the reactant to decompose. $(\log 4 = 0.60)$
Calculate emf of the following cell at 298 K:
$Sn | Sn^{2+}(0.001~M) || H^+(0.01~M) | H_{2(g)}(1~bar) | Pt_{(s)}$
Given: $E^\circ_{Sn^{2+}/Sn} = -0.14~V$, $E^\circ_{H^+/H_2} = 0.00~V [\log 10 = 1]$
60 g of glucose is dissolved in 250 g of water. Calculate the freezing point of this solution.
(molar mass of glucose = $180~g~mol^{-1}$, $K_f$ for water = $1.86~K~kg~mol^{-1}$)
Write the major product in the following reaction: [H]
Complete and balance the following equations:
(i) $2Na_2CrO_4 + 2H^+ \longrightarrow$
(ii) $5S^{2-} + 2MnO_4^- + 16H^+ \longrightarrow$
What happens when 2-Bromobutane is made to react with alcoholic potassium hydroxide?
Indicate the type of isomerism exhibited by the following complex: $[Co(en)_3]Cl_3$
Write the unit of (i) second order reaction and (ii) zero order reaction.
Define Effective collision.
Why second ionization enthalpies of chromium and copper are exceptionally higher than those of their neighbouring elements?
Why transition elements form interstitial compounds?
The concentration of the reactant is reduced from 0.6 mol $L^{-1}$ to 0.2 mol $L^{-1}$ in 5 minutes in a first order reaction. Calculate rate constant of the reaction. $(\log 3 = 0.48)$
Assertion (A): The molecularity of the given reaction is 2
$2HI \longrightarrow H_2 + I_2$
Reason (R): Two molecules of the reactants are involved in simultaneous collision between them.
Assertion (A): Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water.
Reason (R): The carbonyl group is absent in the open chain structure of glucose.
Assertion (A): Zinc, cadmium and mercury are not considered as transition elements.
Reason (R): These elements have completely filled orbitals in their ground state as well as in their common oxidation states.
Assertion (A): Aromatic primary amines can be prepared by Gabriel Phthalimide synthesis.
Reason (R): Aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.
Define coordination number.
Which of the following molecules is chiral in nature?
Which of the following reactions is not explained by the open chain structure of glucose?
Proteins are polymers of $\alpha$-amino acids which are joined to each other by:
The base which is present in DNA but not in RNA is:
Identify the compound produced by the reduction of Ethanenitrile with Lithium aluminium hydride: