List of top Chemistry Questions asked in CBSE CLASS XII

How do you convert:
2-Bromobutane to but-2-ene

What is the difference between native protein and denatured protein?

Give plausible explanation for each of the following:
Amides are less basic than amines.

Arrange the following compounds in increasing order of their boiling point:
\[ \text{(CH}_3\text{)}_2\text{NH, CH}_3\text{CH}_2\text{NH}_2, \text{CH}_3\text{CH}_2\text{OH} \]

Give plausible explanation for each of the following:
Aromatic primary amines cannot be prepared by Gabriel Phthalimide synthesis.

How do you convert:
Propene to 1-Iodopropane

Draw the structure of the major monohalo product for each of the following reactions:

Draw the structure of the major monohalo product for each of the following reactions:

Draw the structure of the major monohalo product for each of the following reactions:

How do you convert:
Chlorobenzene to biphenyl

A certain reaction is 50 complete in 20 minutes at 300 K and the same reaction is 50 complete in 5 minutes at 350 K. Calculate the activation energy if it is a first order reaction.
Given: \[ R = 8.314 \, \text{J K}^{-1} \, \text{mol}^{-1}, \quad \log 4 = 0.602 \]

State the following:
Kohlrausch law of independent migration of ions

Write the reactions involved when D-glucose is treated with the following reagents:
(a) HCN
(b) Br\(_2\) water

Identify A and B in each of the following reaction sequence:
(a) \[ CH_3CH_2Cl \xrightarrow{NaCN} A \xrightarrow{H_2/Ni} B \]
(b) \[ C_6H_5NH_2 \xrightarrow{NaNO_2/HCl} A \xrightarrow{C_6H_5NH_2} B \]

A solution of glucose (molar mass = 180 g mol\(^{-1}\)) in water has a boiling point of 100.20°C. Calculate the freezing point of the same solution. Molal constants for water \(K_f\) and \(K_b\) are 1.86 K kg mol\(^{-1}\) and 0.512 K kg mol\(^{-1}\) respectively.

Complete and balance the following chemical equations:
(a) \[ 2MnO_4^-(aq) + 10I^-(aq) + 16H^+(aq) \rightarrow \]
(b) \[ Cr_2O_7^{2-}(aq) + 6Fe^{2+}(aq) + 14H^+(aq) \rightarrow \]

State the following:
Faraday’s first law of electrolysis

Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal? Justify your answer.

Assertion (A): The boiling points of alkyl halides decrease in the order: RI > RBr > RCl > RF.
Reason (R): The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.

An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because __________

Give reasons:
(a) Cooking is faster in a pressure cooker than in an open pan.
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? What change in temperature would you observe after mixing liquids X and Y?

Assertion (A): The boiling point of ethanol is higher than that of methoxymethane.
Reason (R): There is intramolecular hydrogen bonding in ethanol.

Assertion (A): All naturally occurring \(\alpha\)-amino acids except glycine are optically active.
Reason (R): Most naturally occurring amino acids have L-configuration.

Assertion (A): [Cr(H$_2$O)$_6$]Cl$_2$ and [Fe(H$_2$O)$_6$]Cl$_2$ are examples of homoleptic complexes.
Reason (R): All the ligands attached to the metal are the same.

Alkyl halides undergoing nucleophilic bimolecular substitution reaction involve: