PSEB CLASS 11 CHEMISTRY GUESS PAPER MARCH 2026 SET 1

P.S.E.B. Guess Paper for 2025-26

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) How many significant figures are there in the measurement 0.00345?

• A) 2
• B) 3
• C) 4
• D) 5

(ii) The percentage composition of water (H₂O) is approximately:

• A) 11.19% hydrogen, 88.81% oxygen
• B) 5.90% hydrogen, 94.10% oxygen
• C) 50% hydrogen, 50% oxygen
• D) 10% hydrogen, 90% oxygen

(iii) What is the absolute charge of a proton?

• a) +1.602176×10^-27
• b) –1.602176×10^-19
• c) +1.602176×10^-19
• d) –1.602176×10^-27

(iv) Which of the following models are not the same as Thomson Model of Atom?

• a) plum pudding model
• b) watermelon model
• c) raisin pudding model
• d) nuclear model

(v) Which among the following will have the highest negative electron gain enthalpy?

• a. F
• b. CL
• c. P
• d. S

(vi) The molecule which has zero dipole moment is :

• a. CH₂Cl₂
• b. BF₃
• c. NF₃
• d. ClO₂

(vii) Which of the following is an extensive property?

• a. Molar heat capacity
• b. Temperature
• c. Enthalpy
• d. All of these

(viii) 10^-6 M HCl is diluted to 100 times its pH is:

• (a) 6.0
• (b) 8.0
• (c) 6.95
• (d) 9.5

(ix) Oxidation state of Mn in KMO₄ is:

• a) 6
• b) 5
• c) 7
• d) 8

(x) The shape of methane molecule is?

• a) Linear
• b) Trigonal planar
• c) Square planar
• d) Tetrahedral

State True or False:

(xi) Enthalpy change is always negative for an endothermic process.

(xii) Entropy always increases in a spontaneous process.

(xiii) A reducing agent is itself oxidized during the reaction.

(xiv) In organic compounds, the carbon atom can form bonds with a maximum of four other atoms.

(xv) Aldehydes are more reactive than ketones due to the presence of a hydrogen atom attached to the carbonyl group.

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

Hydrogen has resemblance to alkali metals, which lose one electron to form unipositive ions, as well as with halogens, which gain one electron to form uni-negative ion. Like alkali metals, hydrogen form oxides, halides and sulphides. However, unlike metals, it has a very high ionization enthalpy and does not possess metallic characteristics under normal conditions. In fact, in terms of ionization enthalpy, hydrogen ΔiH of Li is 520 kJmol-1. F is 1689 kJmol-1 and that of H is 1312 kJmol-1. Like halogens, it forms a diatomic molecules. However, in terms of reactivity, it is very low as compared to halogens. In spite of the fact that hydrogen, to a certain extent resembles both with alkali metals and halogens.

(xvi) In what way hydrogen resembles to alkali metals?

(xvii) How hydrogen form unipositive as well as uni-negative ions?

(xviii) Under what conditions hydrogen resembles with halogens?

(xix) Why hydrogen is placed separately in the periodic table?

(xx) Hydrogen, to a certain extent resembles both with alkali metals and halogens. Explain.

SECTION B (2 Marks Each)

Q2. State the law of constant proportions and give an example.

OR

What does Avogadro's hypothesis state?

Q3. What is the mole concept?

Q4. What is an isotope?

Q5. Give two differences between sigma bond and pi bond.

Q6. Write the resonance structures of CO₃^2- And NO₂.

OR

Derive the relationship between Cp and Cv for an Ideal gas.

Q7. Justify Hess’s Law of constant heat Summation with suitable example.

Q8. What do you mean by common ion effect? Explain.

Q9. Define solubility product? Explain briefly

Q10. Give difference between valency and oxidation number.

OR

What do you mean by redox reactions? Explain briefly.

Q11. Explain the concept of functional groups. List any four functional groups and their general characteristics.

Q12. What is the difference between primary, secondary, and tertiary carbon atoms? Provide an example for each.

Q13. Define the term 'hybridization'. Explain the difference between sp, sp², and sp³ hybridization with one example each.

Q14. Write the structures of the products A and B in the following reaction:
HC≡CH → (Na) → A → (CH₃Br) → B

OR

What effect does branching have on the boiling point of an alkane and why?

Q15. Draw New man projection formula for conformations of ethane?

SECTION C (3 Marks Each)

Q16. A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molar mass is 98.96 g. What are its empirical and molecular formulas?

OR

Chlorophyll present in green leaves of plants absorbs light at 4.620 x 10¹⁴ Hz. Calculate the wavelength of radiation in nanometer. Which part of the electromagnetic spectrum does it belong to?

Q17. Derive relationship between Kp & Kc.

Q18. Balance the following equation in acidic medium by oxidation number method. Permanganate ion and Oxalic acid in acidic medium.

OR

Write chemical equations for combustion reaction of the following hydrocarbons:
a) Butane
b) Hexyne
c) Toluene

Q19. Draw the cis and trans structures of hex-2-ene. Which isomer will have higher b.p. and why?

SECTION D (5 Marks Each)

Q20. Using a molecular orbital diagram , predict the bond order , stability and magnetic character of O₂^-,O₂⁺ and O₂^2- ions . Also write their electronic configuration .

OR

State 2nd law of thermodynamics in brief. Discuss the effect of the temperature on the spontaneity of reactions?

Q21. How does benzene react with:
a) Sodium in the presence of dry ether
b) Chlorine in the presence of ferric chloride
c) Nitric acid in the presence of sulphuric acid
d) Hydrogen in the presence of nickel
e) Acetyl chloride in the presence of anhydrous aluminium chloride

OR

explain the following name reactions:
a) Friedel craft alkylation reaction
b) Ozonolysis
c) Wurtz reaction
d) Dehydrohalogenation
e) Etard reaction