Ahsec Class 12 Chemistry Solved Question Paper

Ahsec Class 12 Chemistry Solved Question Paper - 2026| ASSEB BOARD

2026
CHEMISTRY
(Theory)
Full Marks: 70
Pass Marks: 21
Time: 3 hours
The figures in the margin indicate full marks for the questions.

1. Give an example of liquid in solid solution. 1

Ans:- Sodium amalgam (mercury in sodium, Na-Hg) or moisture trapped in a solid.

2. What is the relation between standard electrode potential and reducing power? 1

Ans:- Reducing power is inversely proportional to standard reduction potential (a lower or more negative standard reduction potential implies greater reducing power).

3. Which of the first-row transition elements shows the highest oxidation state? 1

Ans:- Manganese (Mn) (it exhibits oxidation states up to +7, such as in MnO^-₄).

4. Choose the correct answer: 1

The distribution of hybrid orbitals in dsp² hybridization is

(a) tetrahedral

(b) square planar

(c) trigonal pyramidal

Ans:- (b) square planar

5. What is the name of iodine-containing hormone whose deficiency causes goitre? 1

Ans:- Thyroxine (or tetraiodothyronine).

6. What is the name of the following reaction? 1

Ans:- Stephen reaction (or Stephen aldehyde synthesis).

Write the chemical equation of Etard reaction.

Ans:- Chemical equation of the Étard reaction:-

Toluene is oxidized to benzaldehyde using chromyl chloride () in carbon disulfide (), followed by hydrolysis.

7. Why is thionyl chloride preferred to prepare acid chloride from carboxylic acid? 1

Ans:- It is preferred because the by-products formed during the reaction ( and ) are gases that easily escape into the atmosphere, leaving behind a pure sample of the acid chloride without the need for complex separation or purification.

What is the increasing order of rates of dehydration of 1°, 2° and 3° alcohols?

Ans:- Increasing order of rates of dehydration of alcohols:

(This is because the mechanism proceeds via a carbocation intermediate, and tertiary () carbocations are the most stable.)

8. Write the name of the reagent used in the following reaction: 1

Ans:- Stephen reaction (or Stephen aldehyde synthesis).

9. What is Raoult's law? Give an example of non-ideal solution. 2

10. Why does para-nitrophenol possess higher boiling point than ortho-nitrophenol? 2

Ans:- Boiling Point Para-nitrophenol vs. Ortho-nitrophenol:-

(i) Ortho-nitrophenol exhibits intramolecular hydrogen bonding (hydrogen bonding within the same molecule), which prevents association between separate molecules.

(ii) Para-nitrophenol exhibits intermolecular hydrogen bonding (association between separate molecules, forming a chain-like structure). Due to this intermolecular association, extra thermal energy is required to break these hydrogen bonds, resulting in a higher boiling point compared to ortho-nitrophenol.

How will you convert benzene to phenol?

11. State the variation of conductivity and molar conductivity of acetic acid with dilution. 2

Ans:- Changes in Conductivity and Molar Conductivity with Dilution (Acetic Acid):-

(i) Conductivity (Specific Conductance): Decreases with dilution. This is because as the volume of the solution increases, the number of ions per unit volume of the solution decreases.

(ii) Molar Conductivity: Increases rapidly with dilution. For a weak electrolyte like acetic acid, dilution increases the degree of dissociation ($\alpha$), leading to a significant rise in the total number of ions available to carry current in the solution.

12. Explain why Cu⁺ compounds are colourless, but Cu⁺⁺ compounds are coloured. 2