List of top Questions asked in CBSE CLASS XII

What happens when : Chlorobenzene is treated with $CH_{3}Cl$ in the presence of anhydrous $AlCl_{3}$ ?

Assertion (A): Boiling point of propylamine is higher than that of trimethylamine.
Reason (R): In propylamine, intermolecular hydrogen bonding occurs, whereas trimethylamine does not undergo intermolecular hydrogen bonding.

Assertion (A): Rate of reaction increases with an increase in temperature.
Reason (R): Number of effective collisions decreases with an increase in temperature.

Assertion (A): p-nitrophenol is less acidic than phenol.
Reason (R): Nitro group is an electron-withdrawing group, which stabilises the phenoxide ion.

State Raoult's law for a solution containing volatile components. Write any two characteristics of a solution which obeys Raoult's law at all concentrations.

Write any two differences between the order of a reaction and molecularity of a reaction.

In the ring structure of fructose, the anomeric carbon is :

Propan-2-ol on oxidation with $CrO_{3}$ gives :

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 :

Assertion (A): Transition metals have high melting points.
Reason (R): Transition metals have incompletely filled d-orbitals.

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

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 :

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

Which of the following is not a transition metal?

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

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

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

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

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.

Which of the following ligands forms a chelate complex ?