List of top Chemistry Questions asked in CBSE CLASS XII

Which of the following does not undergo Aldol condensation?

Write the chemical equations when:
(a) Ethanal is treated with 2,4-dinitrophenylhydrazine?
(b) Propanone is treated with Zn(Hg) and conc. HCl?
For a chemical reaction \( R \to P \), the variation in the concentration \([R]\) vs time \( t \) plot is given as:
variation in the concentration

(a) Predict the order of the reaction and write the unit of rate constant (\( k \)) for this order of reaction.
(b) What is the slope of the curve?
Assertion (A): \( \Delta_{\text{mix}} H \) for an ideal solution is not equal to zero.
Reason (R): A–B interactions in an ideal solution are the same as between A–A and B–B interactions.
Assertion (A): \( p \)-nitroaniline is a weaker base than \( p \)-toluidine.
Reason (R): The electron-donating \( -NO_2 \) group in \( p \)-nitroaniline makes it a weaker base.
Assertion (A): Fluoroacetic acid is a stronger acid than chloroacetic acid. Reason (R): This is due to greater electron-withdrawing nature of \( F \) than \( Cl \).
All proteins on hydrolysis give:
The suitable Grignard reagent used for the synthesis of
Grignard reagent

with methanal is:
Which of the following has the highest boiling point?
The product (X) obtained in the following reaction is:
product (X) obtained
Which of the following is most reactive towards nucleophilic substitution reaction?
In the Arrhenius equation, when \( \log k \) is plotted against \( 1/T \), a straight line is obtained whose:
A zero-order reaction is one whose rate is independent of:
The system that forms maximum boiling azeotrope is:
Maltose is made up of:
Which of the following is the strongest acid?
The equilibrium \( \text{Cr}_2\text{O}_7^{2-} \rightleftharpoons 2\text{CrO}_4^{2-} \):
Write the chemical equations when: Two molecules of (CH3)3C–CHO are treated with conc. NaOH.
Grignard reagent should be prepared under anhydrous conditions. Give reasons.
In a given graph of zero order reaction, the slope and intercept are:

zero order reaction
Nucleophilic addition of Grignard reagent to ketones followed by hydrolysis with dilute acids forms:
From the elements of 3d series below, which element shows the maximum number of oxidation states?
Which alkyl halide from the given options will undergo S$_N$1 reaction faster?
Rosenmund reduction is used for the preparation of Aldehydes. The catalyst used in this reaction is:
Consider the following reaction:
Identify A and B
Identify A and B from the given options: