List of top Chemistry Questions asked in CBSE CLASS XII

What are essential amino acids?
What is meant by zwitter ionic form of amino acids?
Give one example each for Fibrous protein and Globular protein.
What type of linkages hold monomers of proteins together?
The conductivity of a 0.2 M solution of KCl is \( 2.48 \times 10^{-2} \) S cm\(^{-1}\). Calculate its molar conductivity and degree of dissociation (\( \alpha \)).
Given: \( \lambda^0_{\text{K}^+} = 73.5 \, \text{S cm}^2 \text{mol}^{-1} \), \( \lambda^0_{\text{Cl}^-} = 76.5 \, \text{S cm}^2 \text{mol}^{-1} \)
How will you bring about the following conversions? (any three)
Benzoic acid to Benzaldehyde
Ethanal to Propanone
(c) Acetophenone to Benzoic acid
(d) Bromobenzene to 1-Phenylethanol
Write the reactions involved in the following:
(i) Reimer-Tiemann reaction
(ii) Kolbe’s reaction
Name the reagent used in the bromination of phenol to form 2,4,6-Tribromophenol.
A solution is prepared by dissolving 5 g of a non-volatile solute in 200 g of water. It has a vapor pressure of 31.84 mm Hg at 300 K. Calculate the molar mass of the solute.
(Vapor pressure of pure water at 300 K = 32 mm Hg)
What happens when chlorobenzene and methyl chloride are treated with sodium metal in dry ether?
A first-order reaction is 25% complete in 40 minutes. Calculate the value of the rate constant. In what time will the reaction be 80% complete?
[Given: \( \log 2 = 0.30 \), \( \log 3 = 0.48 \), \( \log 4 = 0.60 \), \( \log 5 = 0.69 \)]
What type of nucleophilic substitution (\( \text{S}_\text{N}1 \) or \( \text{S}_\text{N}2 \)) occurs in the hydrolysis of 2-Bromobutane to form \( (+-) \)-Butan-2-ol? Give reason.
State a condition under which a bimolecular reaction is kinetically a first-order reaction and give an example.
In a reaction, if the concentration of reactant \( X \) is tripled, the rate of reaction becomes twenty-seven times. What is the order of the reaction?
What type of deviation is shown by ethanol and acetone mixture ? Give reason. What type of azeotropic mixture is formed by that deviation ?
Assertion (A): Boiling point of butan-1-ol is higher than that of butan-1-amine. Reason (R): Being more polar, butan-1-ol forms stronger intermolecular hydrogen bonds as compared to butan-1-amine.
Define molal depression constant. How is it related to enthalpy of fusion?
Assertion (A): Rate of reaction decreases with increase in temperature. Reason (R): Number of effective collisions increases with increase in temperature.
Assertion (A): \( \Delta_{\text{mix}} H \) and \( \Delta_{\text{mix}} V \) are zero for an ideal solution. Reason (R): The solution which obeys Raoult’s law over the entire range of concentration is called an ideal solution.
Which of the following cells is used in hearing aids?
The half-life of a first-order reaction with a rate constant (\( k \)) of 3 min\(^{-1}\) is:
A 1% solution of solute ‘X’ is isotonic with a 6% solution of sucrose (molar mass = \( 342 \) g mol\(^{-1}\)). The molar mass of solute ‘X’ is:
Aniline on reaction with Bromine water gives:
CH\(_3\)-O-CH\(_3\) when treated with excess HI gives:
Which of the following Grignard reagents will be used with methanol to prepare
Grignard reagents