List of top Questions asked in CBSE CLASS XII- 2025

At low temperature, phenol reacts with Br$_2$ in CS$_2$ to form:
Assertion (A): A mixture of o-nitrophenol and p-nitrophenol can be separated by steam distillation.
Reason (R): o-nitrophenol is steam volatile due to intermolecular hydrogen bonding.

In the reaction R–OH + HCl $\xrightarrow{\text{ZnCl}_2}$ RCl + H$_2$O, what is the correct order of reactivity of alcohols?

The reaction

suggests that phenol is :

Assertion (A): The boiling point of ethanol is higher than that of methoxymethane.
Reason (R): There is intramolecular hydrogen bonding in ethanol.
The conversion of phenol to salicylic acid can be accomplished by
What will be formed after oxidation reaction of secondary alcohol with chromic anhydride (CrO$_3$)?
The conversion of phenol to salicylic acid can be accomplished by
Phenol reacts with Bromine (Br$_2$) water to form:
Scurvy is caused due to deficiency of
$\alpha$-helix structure refers to:
Assertion (A): Vitamin K can be stored in our body.
Reason (R): Vitamin K is a water soluble vitamin.
‘Scurvy’ is caused due to the deficiency of:

Assertion (A): Maltose is a reducing sugar.
Reason (R): One of the two glucose units can open to expose free aldehydic group in solution.

Assertion (A): All naturally occurring \(\alpha\)-amino acids except glycine are optically active.
Reason (R): Most naturally occurring amino acids have L-configuration.
Scurvy is caused due to deficiency of
Nucleotides are joined together by
Which of the following is/are examples of denaturation of protein?
Nucleotides are joined together by
Deficiency of vitamin B$_1$ causes the disease :
Assertion (A): Vitamin C cannot be stored in our body.
Reason (R): Vitamin C is water soluble and excreted in urine.
Standard electrode potential for Sn$^{4+}$/Sn$^{2+}$ couple is +0.15 V and that for the Cr$^{3+}$/Cr couple is -0.74 V. The two couples in their standard states are connected to make a cell. The cell potential will be:
Assertion (A): Cu cannot liberate \( H_2 \) on reaction with dilute mineral acids. Reason (R): Cu has positive electrode potential.

What amount of electric charge is required for the reduction of 1 mole of MnO$_4^{2-}$ into Mn$^{2+}$?

Assertion (A): Electrolysis of aqueous NaCl gives H$_2$ at cathode and Cl$_2$ at anode.
Reason (R): Chlorine has higher oxidation potential than H$_2$O.