P.S.E.B. Guess Paper for 2025-26
Class 12th
Subject: Chemistry
Time: 3 Hours | Max. Marks: 70
Instructions: Question 1 contains 20 parts of 1 mark each. Question 2 to 15 are of 2 marks each. Question 16 to 19 are of 3 marks each. Question 20 and 21 are of 5 marks each. All questions are compulsory.
Q1. Choose the correct answer / True-False / Comprehension
(i) The mole fraction of urea in an aqueous urea solution containing 900 g of water is 0.05. If the density of the solution is 1.2 g cm-3, the molarity of urea solution is:
(ii) The cell constant of a conductivity cell:
(iii) In a first-order reaction, the rate constant is:
(iv) Which of the following has square planar structure?
(v) Alkyl halides react with KCN to give as the major product:
(vi) Monochlorination of toluene in sunlight followed by hydrolysis with aq. NaOH yields:
(vii) The strongest acid among the following compounds is:
(viii) Amongst the following, the strongest base in aqueous medium is:
(ix) Which amino acid has an Imidazole ring?
(x) Molecular formula of ethers is:
True/False
(xi) [Fe(CN)6]3- ion shows magnetic moment corresponding to two unpaired electrons.
(xii) EDTA4- is ethylene diamine tetra acetate.
(xiii) Acetaldehyde can be reduced to ethane in the presence of LiAlH4.
(xiv) Amines act as Lewis bases.
(xv) Formic acid gives Silver mirror test with Tollens Reagent.
Read the passage and answer the questions (xvi) to (xx)-
Carbohydrates are optically active polyhydroxy aldehydes and ketones. They are also called saccharides. All those carbohydrates which reduce Fehling's solution and Tollen's reagent are referred to as reducing sugars. Glucose, the most important source of energy for mammals, is obtained by the hydrolysis of starch. Vitamins are accessory food factors required in the diet. Proteins are the polymers of amino acids and perform various structural and dynamic functions in the organisms. Deficiency of vitamins leads to many diseases.
(xvi) What are reducing sugars?
(xvii) What is the basic structural unit of proteins?
(xviii) Define Glycosidic linkage as related to carbohydrates.
(xix) Name the disease caused by deficiency of vitamin C.
(xx) What is the food reserve in plants?
2 Marks Questions
Q2. Define Molality of a solution. What is the effect of temperature on Molality?
Q3. What is a Salt bridge? Write the functions of a Salt bridge.
Q4. Define order and molecularity of a reaction with examples.
OR
Define activation energy. Explain with a diagram.
Q5. Why do transition metals show variable oxidation states?
Q6. Explain the difference between a Weak field ligand and a Strong field ligand.
Q7. How will you distinguish between benzyl bromide and p-bromotoluene?
Q8. Explain why for a given alkyl group, the order of reactivity is RI > RBr > RCl > RF?
OR
Explain why chlorine present in chlorobenzene is ortho and para-directing.
Q9. Write down the distinguishing test between an aldehyde and a Ketone.
Q10. What is the carbylamine reaction?
Q11. What is the difference between Essential amino acids and Non-essential amino acids?
Q12. Calculate the mole fraction of ethanol and water in a sample which contains 95% ethanol by mass.
OR
A sugar syrup of weight 214.2 g contains 34.2 g of sugar (C12H22O11). Calculate the mole fraction of sugar in the syrup.
Q13. State Faraday's laws of electrolysis.
Q14. A first order reaction takes 23.1 min for 50% completion. Calculate the time required for 75% completion of this reaction.
Q15. How can you carry out nitration in phenol? Give the equation.
3 Marks Questions
Q16. The resistance of 0.25 molar solution of an electrolyte was found to be 75 Ω. Calculate the molar conductivity of the solution if the electrodes in the cell are 1.8 cm apart, having an area of cross section of 3.6 cm2.
Ni(s) + 2Ag+(aq) → Ni2+ (aq) + 2Ag(s)
Given: E° = 1.05V, 1F = 96500C mol-1
OR
Find the values of equilibrium constant (Kc) and ΔG° for the reaction:Ni(s) + 2Ag+(aq) → Ni2+ (aq) + 2Ag(s)
Given: E° = 1.05V, 1F = 96500C mol-1
Q17. The rate constant of a reaction becomes six times when the temperature is raised from 350K to 400K. Calculate the activation energy of the reaction. (Given R = 8.314 JK-1mol-1)
Q18. Write Hinsberg’s test to distinguish between 1°, 2° and 3° amines.
Q19. How will you account for the acidic nature of carboxylic acids?
OR
Discuss the Hell-Volhard-Zelinsky reaction of carboxylic acids.
5 Marks Questions
Q20. (a) Account for the following:
(i) Transition metals show variable oxidation states.
(ii) Zn, Cd and Hg are soft metals.
(iii) E° value for the Mn3+/Mn2+ couple is highly positive (+ 1.57 V) as compared to Cr3+/Cr2+.
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
(i) Transition metals show variable oxidation states.
(ii) Zn, Cd and Hg are soft metals.
(iii) E° value for the Mn3+/Mn2+ couple is highly positive (+ 1.57 V) as compared to Cr3+/Cr2+.
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
OR
What is meant by ‘lanthanoid contraction’? Explain the cause and consequences of lanthanoid contraction.
Q21. How would you bring about the following conversions:
(i) Propene to 2-bromopropane
(ii) Bromoethane to propanoic acid
(iii) 1-chloropropane to 1-propanol
(iv) Ethanol to chloroethane
(v) 1-iodopropane to propene
(i) Balz Schiemann reaction
(ii) Sulphonation of Haloarenes
(iii) Sandmeyer’s reaction
(iv) Finkelstein reaction
(v) Ullmann reaction
(i) Propene to 2-bromopropane
(ii) Bromoethane to propanoic acid
(iii) 1-chloropropane to 1-propanol
(iv) Ethanol to chloroethane
(v) 1-iodopropane to propene
OR
Explain the following reactions:(i) Balz Schiemann reaction
(ii) Sulphonation of Haloarenes
(iii) Sandmeyer’s reaction
(iv) Finkelstein reaction
(v) Ullmann reaction
