PUNJAB BOARD 10+2 CHEMISTRY GUESS QUESTION PAPER 2025 SET 2

Punjab Board Class 12 Chemistry Guess Paper 2025

Are you preparing for the Punjab Board Class 12 Chemistry Exam 2025? Get the most important questions and a detailed guess paper to score high in your PSEB 12th Chemistry board exam.

Why This Chemistry Guess Paper is Important?

• Prepared according to the latest PSEB syllabus.
• Includes MCQs, short answer, and long answer questions.
• Covers high-weightage topics for better exam preparation.
• Designed to help students score above 90% marks.

How to Use This Guess Paper for Punjab Board Chemistry Exam?

Follow these expert tips to maximize your preparation:

• Revise the important topics and practice previous year questions.
• Time yourself while solving this guess paper to improve speed.
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• Use NCERT books along with this PSEB Chemistry Model Paper 2025.

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PUNJAB BOARD 10+2 CHEMISTRY GUESS QUESTION PAPER 2025 

Total Marks: 70     Time: 3 Hours

Instructions:

• All questions are compulsory.
• Q. No. 1 has 15 parts carrying one mark each.
• Q. No. 2 to 15 carry 2 marks each.
• Q. No. 16 to 19 carry 3 marks each.
• Q. No. 20 to 21 carry 5 marks each.

SECTION A - One Mark Questions (MCQs & True/False)

1. The IUPAC Name of [Pt(NH₃)₂Cl(NO₂)] is:
   (a) Platinumdiaminechloronitrite
   (b) Chloronitrito-N-ammineplatinum(II)
   (c) Diamminechloridonitrito-N-platinum(II)
   (d) Diamminechloronitrito-N-platinate(II)
2. The unit of cell constant is:
   (a) cm⁻¹    (b) cm²    (c) cm    (d) Scm²
3. Which of the following is the strongest acid?
   (a) CH₃COOH    (b) CH₃CH₂CH₂COOH    (c) HCOOH    (d) CH₃CH₂COOH
4. The chemical reaction 2HCHO ---(Conc NaoH ----> CH₃OH +  HCOONa represents:
   (a) Rosenmund’s reaction.
   (b) Kolbe’s reaction.
   (c) Cannizzaro’s reaction.
   (d) Etard’s reaction.
5. For distinction between pentan-2-one and pentan-3-one, which reagent can be employed?
   (a) K₂Cr₂O₇/H
   (b) ZnHg/HCl
   (c) NaOH/I₂
   (d) AgNO₃/NH₄OH
6. Which of the following is NOT affected by temperature?
   (a) Normality    (b) Molality    (c) Molarity    (d) Formality
7. The reaction of Iodobenzene with copper powder in a sealed tube to give diphenyl is called:
   (a) Ullmann reaction
   (b) Hunsdiecker reaction
   (c) Gattermann reaction
   (d) Fittig reaction
8. Molality is expressed as:
   (a) L/mol    (b) mol/kg    (c) mol/1000g    (d) g/L
9. Mole fraction of a solute in 2.5M aqueous solution is:
   (a) 0.43    (b) 0.043    (c) 4.3    (d) 43
10. Aldehydes and ketones react with electrophiles but not with nucleophiles. (True/False)
11. [Ni(CN)₄]²⁻ is square planar. (True/False)
12. Acetaldehyde can be reduced to ethane in the presence of LiAlH₄. (True/False)
13. Alcohols are more soluble in water than hydrocarbons. (True/False)
14. Chelate complexes tend to be more stable. (True/False)
15. Bimolecular reaction, if one of the reactants is in excess, is called:
    (a) Pseudo First order
    (b) Zero Order
    (c) Second Order
    (d) Third Order

SECTION B - Comprehension

Nucleic acids refer to the genetic material found in the cell that carries all hereditary information from parents to progeny. There are two types of nucleic acids, namely, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The main function of nucleic acids is the transfer of genetic information and synthesis of proteins by processes known as translation and transcription. The monomeric unit of nucleic acids is known as a nucleotide and is composed of a nitrogenous base, pentose sugar, and phosphate. The nucleotides are linked by a 3’ and 5’ phosphodiester bond. The nitrogen base attached to the pentose sugar makes the nucleotide distinct. There are four major nitrogenous bases found in DNA: adenine, guanine, cytosine, and thymine. In RNA, thymine is replaced by uracil. The DNA structure is described as a double-helix or double-helical structure, which is formed by hydrogen bonding between the bases of two antiparallel polynucleotide chains.

Answer the following questions:

1. Name the base that is not found in DNA.
2. Which nucleic acid helps in protein synthesis?
3. What is the composition of a nucleotide?
4. Write any one difference between DNA and RNA.
5. Which bond provides stabilization to the double helical structure of DNA?

SECTION B - Questions Carrying Two Marks

1. Write the difference between the rate of reaction and rate constant.
2. Write the uses of ether.
3. Calculate mole fraction of water in a mixture of 12g of water and 92g ethanol.
4. Define the corrosion and give the name of the chemical formula of rust.
5. Write IUPAC names of the following compounds:
       1) K₂[PtCl₄]
       2) [CoBr₂(en)₂]Cl
6. Why are boiling points of carboxylic acids higher than the corresponding alcohols?
7. What is the chemical name of Vitamin D, and which disease is caused by its deficiency?
8. State Henry’s Law and write its two applications.
9. How is the presence of primary amine confirmed by Carbylamine reaction?
10. Write and explain Aldol condensation.
11. Why is aniline less basic than ethylamine?
12. A first-order reaction is found to have a rate constant, k = 5.5 × 10⁻¹⁴ s⁻¹. Find two-third life period of the reaction.
       Or
       Calculate the half-life of a first-order reaction having K = 4.93 × 10⁻⁴ s⁻¹.
13. Write the short note on coupling reaction.
14. Write the general electronic configuration of d-block and f-block elements.
15. If a current of 0.5 amp flows through a metallic wire for 2 hours, then how many electrons flow through the wire?

SECTION C - Questions Carrying Three Marks

1. Discuss the reaction and mechanisms of acidic dehydration of ethyl alcohol to prepare ether.
      Or
      Explain why phenol is more acidic than alcohol.
2. Write the reactions involved in the following:
       (i) Hofmann bromamide degradation reaction
       (ii) Gabriel phthalimide synthesis
3. A cell reaction is Ni (s) | Ni²⁺_(0.01M) || Cu²⁺_(0.01M) | Cu(s). Calculate E_cell of a reaction and also write Nernst equation.
       Given: E°(Ni²⁺ | Ni) = -0.22 V and E°(Cu²⁺ | Cu) = 0.34 V
4. The rate of the chemical reaction doubles for an increase of 10 K in absolute temperature from 298K. Calculate E_a.
5. The molar conductance of infinite dilution for sodium acetate (CH₃COONa), hydrochloric acid (HCl), and sodium chloride (NaCl) are 95.5, 426.9, and 120.4 S cm² mol⁻¹, respectively, at 298 K. Calculate the molar conductance of Acetic Acid (CH₃COOH) at infinite dilution.

SECTION D - Questions Carrying Five Marks

1. Why are Zn, Cd, and Hg non-transition elements?
       (ii) Which transition metal of 3d series does not show variable oxidation states?
       (iii) Why do transition metals and their compounds show catalytic activity?
       (iv) Why are melting points of transition metals high?
       (v) Why is Cu²⁺ ion coloured while Zn²⁺ ion is colourless in aqueous solution? OR i) Write the similarities between Lanthanides and Actinides  ii)   Write the difference between Lanthanides and Actinide elements.
2. Explain the following reactions:
       (a) Balz-Schiemann reaction
       (b) Finkelstein reaction
       (c) Ullmann reaction
       (d) Swarts reaction
       (e) Gattermann reaction

OR Why are aryl halides ortho and para directing?