List of top Questions asked in CBSE CLASS XII- 2026

Chloroform, in the presence of air and sunlight, produces a poisonous gas known as:

The reaction of ammonia with a large excess of ethyl chloride will give mainly :

Acetamide reacts with $Br_{2}$ and aqueous KOH to form :

The rate of a reaction is doubled when the concentration of the reactant is doubled. The order of the reaction is :

Vitamin $B_{12}$ is a complex compound of :

For an electrolyte consisting of a monovalent cation and a monovalent anion undergoing dissociation in water, the van't Hoff factor (i) is :

The secondary valency of Co in $[Co(en)_{3}]_{2}(SO_{4})_{3}$ is:

Which of the following is not a transition metal?

The standard electrode potentials of three metals A, B and C are, respectively, + 0.34 V, - 1.18 V and - 0.25 V. The correct order of reducing power of these metals is :

Which of the following colligative properties can preferably determine the molar mass of proteins ?

The rate of a particular reaction quadruples when the temperature increases from 300 K to 320 K. Calculate the energy of activation \( (E_a) \) of the reaction assuming that it does not change with temperature.
(Given : \( \log 4 = 0 \cdot 60, R = 8 \cdot 314 \text{ JK}^{-1} \text{ mol}^{-1} \))

Calculate emf of the following cell at 298 K :
\( \text{Zn (s)| Zn}^{2+}\text{(aq) (0.1 M)|| Ag}^+\text{ (aq) (0.01 M)|Ag (s)} \)
(Given : \( E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \text{ V}, E^\circ_{\text{Ag}^{+}/\text{Ag}} = +0.80 \text{ V, [log 10 = 1]} \))

Assertion (A) : All aliphatic aldehydes give a positive Fehling’s test.
Reason (R) : Aliphatic aldehydes are reduced by Fehling’s reagent.

Assertion (A) : D (+) – Glucose is dextrorotatory in nature.
Reason (R) : (+) represents dextrorotatory nature and D represents the configuration.

Which of the following ligands forms a chelate complex ?

Assertion (A) : Highest oxidation state of Mn is +7 in first series of transition elements.
Reason (R) : Transition metals exhibit variable oxidation states.

Assertion (A) : p-nitrophenol is more acidic than phenol.
Reason (R) : Nitro group is an electron-withdrawing group, it stabilises phenoxide ion by dispersal of negative charge.

The polypeptide chain in a protein has amino acids linked with each other in a specific sequence. This specific sequence of amino acids is called :

Half-life \( (t_{1/2}) \) of a first order reaction is 1386 s. The value of rate constant is :

Identify the polysaccharide among the following :

Actinoids show larger number of oxidation states :

Consider the following compounds :
\( \text{C}_2\text{H}_5\text{NH}_2, (\text{C}_2\text{H}_5)_2\text{NH}, \text{C}_6\text{H}_5\text{CH}_2\text{NH}_2, \text{NH}_3, \text{C}_6\text{H}_5\text{NH}_2 \)
The correct increasing order of the above compounds on the basis of their basic strength is :

Primary, secondary and tertiary alcohols can be distinguished by :

Consider the following reaction and identify A and B :
\( \text{CH}_3\text{Cl} + \text{NaI} \xrightarrow{\text{dry acetone}} \text{A} + \text{B} \)

Which of the reactions is used in the conversion of a ketone into hydrocarbon ?