PSEB CLASS 11 CHEMISTRY GUESS PAPER MARCH 2026 SET 3

P.S.E.B. Guess Paper for 2025-26 (Set 3)

Class 11th (10+1)

Subject: Chemistry

Time: 3 Hours                                                                                         Max. Marks: 70

General Instructions:

1. There is one theory paper comprising 21 questions. All questions are compulsory.
2. Question No. 1 has 20 sub-parts carrying 1 mark each. This question contains multiple-choice, true/false, and comprehension-based questions.
3. Question No. 2 to 15 are of 2 marks each. There is an internal choice in four questions.
4. Question No. 16 to 19 are of 3 marks each. There is an internal choice in two questions.
5. Question No. 20 and 21 are of 5 marks each. There is an internal choice in both of them.

SECTION A (1 Mark Each)

Q1. Answer the following questions (i to xx):

Choose the correct answer (MCQs):

(i) Which of the following is NOT a basic unit of measurement in the International System of Units (SI)?

• A) Meter
• B) Kilogram
• C) Kelvin
• D) Pound

(ii) Find out the number of neutrons, protons, and electrons of ₁₇Cl³⁷ respectively:

• A) 20, 20, 17
• B) 17, 17, 20
• C) 20, 17, 17
• D) 17, 17, 17

(iii) The radius of an atomic nucleus is of the order of:

• A) 10^-10 cm
• B) 10^-13 cm
• C) 10^-15 cm
• D) 10^-8 cm

(iv) The species having bond angle of 120° is:

• A) ClF₃
• B) NCl₃
• C) BCl₃
• D) PH₃

(v) What condition facilitate the spontaneity of a reaction if ΔH and ΔS both are negative?

• A) Low temperature
• B) High temperature
• C) Low pressure
• D) High pressure

(vi) In a chemical reaction A ⇌ B, the system will be known in equilibrium when:

• A) A completely changes to B
• B) 50% of A changes to B
• C) The rate of change of A to B and B to A on both the sides are same
• D) Only 10% of A changes to B

(vii) The Oxidation number of Cr in K₂Cr₂O₇ is:

• A) 6
• B) 5
• C) 0
• D) 4

(viii) The bond length in CH₄ is:

• A) 1.09 Å
• B) 1.54 Å
• C) 1.46 Å
• D) 1.12 Å

(ix) The displacement of electrons in a multiple bond in the presence of attacking reagent is called:

• A) Inductive effect
• B) Electromeric effect
• C) Resonance
• D) Hyperconjugation

(x) Which of the following is a property of benzene (C₆H₆)?

• A) It has a resonance structure.
• B) It is highly reactive and undergoes nucleophilic substitution.
• C) It undergoes addition reactions easily.
• D) It is a saturated compound.

State True or False:

(xi) (q+w) is a state function.

(xii) In an isochoric process the volume change is zero.

(xiii) At anode always oxidation takes place.

(xiv) Entropy of a perfectly crystalline solid is taken as zero at 0K.

(xv) Sulphur in an organic compound can be estimated by Dumas method.

Read the passage and answer the questions (xvi to xx):

In the long form of the periodic table, elements are arranged in increasing order of their atomic numbers, which in turn, determine their electronic configurations and hence their properties. All the 118 elements known todate are divided into four blocks: s, p, d and f depending upon the name of the orbital which receives the last electron. All these elements have also been classified as representative elements, transition elements and inner transition elements depending upon whether their properties solely depend upon n (valence) electrons, n and n - 1 electrons or n, (n - 1) and (n - 2) electrons respectively. Elements with Z > 100 also called super heavy elements have also been given IUPAC names and symbols.

(xvi) Write the general electronic configuration of s-block elements.

(xvii) How many groups of p-block elements are there in the long form of the period table?

(xviii) Which block in periodic table is called transition elements?

(xix) On which basis the elements in modern periodic table are arranged?

(xx) Write the IUPAC name of element with At.no. = 114.

SECTION B (2 Marks Each)

Q2. Calculate the mass per cent of oxygen element present in sodium sulphate (Na₂SO₄).

OR

Calculate the molarity of Glucose (C₆H₁₂O₆) solution 20 g of which are dissolved in two litres of solution.

Q3. Define isotones. Give one example.

Q4. What is the e/m ratio of an electron?

Q5. Give two points of difference between a sigma bond and a pi bond.

Q6. Explain the conditions in terms of ΔH and ΔS when a reaction would be always spontaneous.

OR

Explain Hess's law of constant heat of summation.

Q7. Justify that the reaction : 2 Cu₂O (s) + Cu₂S (s) → 6 Cu (s) + SO₂ (g) is a redox reaction. Identify the species oxidised/reduced, which acts as an oxidant and which acts as a reductant.

Q8. Explain the term 'ionic product of water'.

Q9. The concentration of hydrogen ion in a sample of soft drink is 3.8 x 10^-3 M. What is its pH?

OR

Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for: (a) 2,2,4-Trimethylpentan-3-one (b) 2-Hydroxyhexane-1,6-dial.

Q10. Draw the cis- and trans- structures for hex-2-ene. Which isomer will have higher boiling point and why?

Q11. What is the difference between primary, secondary, and tertiary carbon atoms? Provide an example for each.

Q12. What are the necessary conditions for any system to be aromatic?

Q13. Why HF has a higher boiling point than HCl?

OR

Out of NH₃ and PH₃, which has higher boiling point and why?

Q14. Define enthalpy of combustion.

Q15. Write the structures of the products A and B in the following reaction:
HC≡CH → (Na) → A → (CH₃Br) → B

SECTION C (3 Marks Each)

Q16. A compound contains 9.1% hydrogen, 54.4% carbon and rest is oxygen. Its vapour density is 44. What are its empirical and molecular formulas?

OR

A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1 Å. What is the uncertainty involved in the measurement of its velocity?

Q17. Balance the following equation by the oxidation number method:
Fe²⁺ + Cr₂O₇^2- → Cr³⁺ + Fe³⁺ (acidic medium)

Q18. (a) Define electrophile.
(b) Give a chemical reaction showing an example of each: Nucleophilic substitution and Electrophilic addition reactions.

OR

Calculate the maximum work obtained when 0.75 mol of an ideal gas expands isothermally and reversibly at 27°C from a volume of 15 L to 25 L.

Q19. Discuss the concept of resonance with reference to the nitrate ion. Draw its resonance structures.

SECTION D (5 Marks Each)

Q20. (a) On the basis of VSEPR theory predict the geometry and shape of ClF₃. (3 Marks)
(b) Find the formal charge on Nitrogen in Nitrate ion. (2 Marks)

OR

(a) On the basis of Hybridization predict the geometry and shape of SF₄. (3 Marks)
(b) Draw energy level diagram of O₂⁺. (2 Marks)

Q21. (a) An alkene 'A' on ozonolysis gives a mixture of ethanal and pentan-3-one. Write the structure and IUPAC name of alkene. Show ozonolysis reaction of this alkene. (3 Marks)
(b) Give chemical equations for the following name reactions: Wurtz reaction and Friedel Craft alkylation. (2 Marks)

OR

Discuss the mechanism of nitration of benzene in detail.