List of top Chemistry Questions asked in CBSE CLASS XII

Account for the following:
Conductivity of CH\(_3\)COOH decreases on dilution.

Which vitamin is responsible for the coagulation of blood?

Which one of the following is a disaccharide?
\[ \text{Glucose, Lactose, Amylose, Fructose} \]

What is the difference between native protein and denatured protein?

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

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

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

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

How do you convert:
Propene to 1-Iodopropane

How do you convert:
Chlorobenzene to biphenyl

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:

Using \( E^\circ \) values of X and Y given below, predict which is better for coating the surface of iron to prevent corrosion and why?
Given: \( E^\circ_{X^{2+}/X} = -2.36 \, \text{V} \) \( E^\circ_{Y^{2+}/Y} = -0.14 \, \text{V} \) \( E^\circ_{Fe^{2+}/Fe} = -0.44 \, \text{V} \)

State the following:
Faraday’s first law of electrolysis

State the following:
Kohlrausch law of independent migration of ions

Read the passage carefully and answer the questions that follow.
Passage: The rate of a chemical reaction is expressed either in terms of decrease in the concentration of reactants or increase in the concentration of a product per unit time. Rate of the reaction depends upon the nature of reactants, concentration of reactants, temperature, presence of catalyst, surface area of the reactants and presence of light. Rate of reaction is directly related to the concentration of reactant. Rate law states that the rate of reaction depends upon the concentration terms on which the rate of reaction actually depends, as observed experimentally. The sum of powers of the concentration of the reactants in the Rate law expression is called order of reaction while the number of reacting species taking part in an elementary reaction which must collide simultaneously in order to bring about a chemical reaction is called molecularity of the reaction.
 Answer the following questions:

The elements of 3d transition series are given as: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn
Answer the following:

The role of a catalyst is to change _____________ .

Why is [Ni(CN)4]2- square planar while [Ni(CO)4] is tetrahedral? [Atomic number : Ni = 28]

Identify A and B in the following reactions:

Shweta mixed two liquids A and B of 10 mL each. After mixing, the volume of the solution was found to be 20.2 mL.
(i) Why was there a volume change after mixing the liquids?
(ii) Will there be an increase or decrease of temperature after mixing?
(iii) Give one example for this type of solution.

Give a chemical test to distinguish between benzaldehyde and acetophenone.

Which of the following molecules is chiral in nature?

While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution?

Tertiary alkyl halides are least reactive towards SN2 reaction.