List of top Questions asked in CBSE CLASS XII

Why are the products of electrolysis different for the electrolysis of aqueous solution of \( AgNO_{3} \) with silver electrodes and electrolysis of aqueous solution of \( AgNO_{3} \) with platinum electrodes?
Why are magnesium blocks fixed to the iron pipelines carrying water?
What happens when: p-fluorotoluene is treated with \( CrO_{3} \) in the presence of acetic anhydride followed by hydrolysis with aqueous acid?
What happens when: Phthalic acid is treated with \( NH_{3} \) followed by heating?
When a coordination compound \( CoCl_{3} \cdot 6NH_{3} \) is mixed with excess of \( AgNO_{3} \) solution, 3 moles of \( AgCl \) are precipitated per mole of the compound. Write the structural formula of the complex, IUPAC name, its hybridisation and magnetic behaviour on the basis of valence bond theory.
Why is direct current (DC) not used to measure the resistance of an ionic solution?
Write the structures of A, B and C in the following reaction:
Draw the structure of the major product in the following reaction: \( CH_{3}CH = C(CH_{3})_{2} + HBr \rightarrow \)
What happens when: Propanenitrile is treated with phenyl magnesium bromide followed by hydrolysis?
Write the structures of A, B and C in the following reaction:
Draw the structure of the major product in the following reaction:
What are the hydrolysis products of the following ? Lactose
What are the hydrolysis products of the following ? DNA containing Thymine
State the condition under which a bimolecular reaction may be kinetically a first order reaction.
Write IUPAC name of the following compound : \( [Cr(NH_{3})_{4} (ONO)Cl] NO_{3} \)
Explain the following with the help of Henry’s law : (i) Bends (ii) Anoxia
Write IUPAC name of the following compound : \( Na[Ag(CN)_{2}] \)
Assertion (A) : Diazonium salts of aromatic amines are more stable than those of aliphatic amines.
Reason (R) : Diazonium salts of aliphatic amines undergo resonance.
Reactions of which order will show the rate to be independent of the concentration of the reactant ? Give one example of this order.
Assertion (A) : \( E^{\circ}_{Sc^{3+}/Sc^{2+}} \) has low value.
Reason (R) : Because of the stability of \( Sc^{3+} \) ion which has a noble gas configuration.
Assertion (A) : Alcohols act as Bronsted bases as well as Bronsted acids.
Reason (R) : It is due to the presence of unshared electron pairs on oxygen atom and presence of polar \( O - H \) bond.
Assertion (A) : For complex reaction, order of reaction is given by the slowest step.
Reason (R) : Order of a reaction is an experimental quantity.
In the reaction of \( NaOBr \) with amide, the carbonyl carbon is lost as :
When a liquid and its vapour are at equilibrium and the pressure is suddenly decreased :
Nucleic acids are polymers of :