Solved question paper for Chemistry Mar-2021 (PSEB Class 12th)

Solved Question Paper

Chemistry Mar-2021

PSEB • Class 12th • 1st • Mar-2021

Chemistry previous year question papers on BRpaper help students looking for PSEB 12th Class Question Papers to browse Chemistry papers for board exam practice and revision. This subject section is useful for finding PSEB 12th Chemistry old question papers, PYQ-style papers, and related exam-preparation material where available, so students can study the question format, recurring topics, and marks pattern used in the Punjab board exam. If you are preparing for the Punjab School Education Board Class 12 Chemistry paper, this page can help you compare past question styles with sample paper and model paper trends, and focus on important questions more confidently. BRpaper is not the official website of Punjab School Education Board or any institution, and it does not publish official notices or academic updates.

Solved Questions

Solved
  1. Which type of colloids are stable in nature?
    Short Answer Mar-2021 • PSEB Class 12th
  2. Define lyophilic colloids.
    Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  3. Which type of colloids undergo solvation?
    Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  4. What are protective colloids?
    Short Answer Mar-2021 • PSEB Class 12th
  5. How protection of colloids can be done?
    Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  6. The C-X bond length in halobenzene is smaller than C-X bond length in CH3-X
    True / False 1 Marks Mar-2021 • PSEB Class 12th
  7. Alcohols are weaker acids than water
    True / False 1 Marks Mar-2021 • PSEB Class 12th
  8. Carboxylic acids are more acidic than phenols.
    True / False 1 Marks Mar-2021 • PSEB Class 12th
  9. Keratin is fibrous protein
    True / False 1 Marks Mar-2021 • PSEB Class 12th
  10. Aliphatic Amines are more basic than NH3
    True / False 1 Marks Mar-2021 • PSEB Class 12th
  11. which of the following aqueous solutions have should have the highest boiling point : (a) 1.0 M NaOH (b) 1.0 M Na2SO4 (c) 1.0 M NH4NO3 (d) 1.0 M KNO3
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  12. The value of Henry’s constant : (a) Increases with increase in temp (b) decreases with increase in temp (c) remains contant (d) first increases the decreases
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  13. 18 g of glucose is dissolved in 1kg of water at what temp will the water boil , kb for water is 0.52 K kg mol-1 (a) 373.2 K (b) 378.2 K (c) 381.5 K (d)
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  14. Which of the followings oxidation state of oxygen is +2 (a) Cl2O (b) O2F2 (c) OF2 (d) N2O
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  15. Ethanol upon heating with conc. H2SO4 at 443 k gives: (a) Diethyl ether (b) Ethylene (c) Ethyl hydrogen sulphate (d) none of these
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  16. Oxidation state of Fe in [Fe(CN)6 ]3-
    MCQ 1 Marks Mar-2021 • PSEB Class 12th
  17. Lyophilic sols are more stable than lyophobic sols. This is due to the fact that lyophilic colloids are extensively solvated, i.e., colloidal particles are covered by a sheath of the liquid in which they are dispersed.Lyophilic colloids have a unique property of protecting lyophobic colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around
    lyophobic particles and thus protect the latter from electrolytes. Lyophilic colloids used for this purpose are called protective colloids.

    Answer the followings

    Which type of colloids are stable in nature?
    Define lyophilic colloids.
    Which type of colloids undergo solvation?
    What are protective colloids?
    How protection of colloids can be done?
    Very Short Answer 5 Marks Mar-2021 • PSEB Class 12th
  18. True/False

    The C-X bond length in halobenzene is smaller than C-X bond length in CH3-X (T/F)
    Alcohols are weaker acids than water (T/F)
    Carboxylic acids are more acidic than phenols. (T/F)
    Keratin is fibrous protein ( T/F)
    Aliphatic Amines are more basic than NH3 ( T/F)
    True / False 5 Marks Mar-2021 • PSEB Class 12th
  19. which of the following aqueous solutions have should have the highest
    boiling point :
    (a) 1.0 M NaOH
    (b) 1.0 M Na2SO4
    (c) 1.0 M NH4NO3
    (d) 1.0 M KNO3
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  20. Colligative properties depends upon :
    (a) Nature of solute particles present in the solution
    (b) Nature of solute particles present in the solution
    (c) Physical properties of the solute particles
    (d) Nature of the solvent particles
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  21. The value of Henry’s constant :
    (a) Increases with increase in temp
    (b) decreases with increase in temp
    (c)remains contant
    (d) first increases the decreases
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  22. 18 g of glucose is dissolved in 1kg of water at what temp will the water boil ,
    kb for water is 0.52 K kg mol-1
    (a)373.2 K
    (b) 378.2 K
    (c) 381.5 K
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  23. Which of the followings oxidation state of oxygen is +2
    (a) Cl2O
    (b) O2F2
    (c) OF2
    (d) N2O
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  24. Ethanol upon heating with conc. H2SO4 at 443 k gives:
    (a) Diethyl ether
    (b) Ethylene
    (c) Ethyl hydrogen sulphate
    (d) none of these
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  25. Oxidation state of Fe in [Fe(CN)6 ]3-
    (a) +3
    (b) +2
    (c) +4
    (d) -3
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  26. IUPAC name of the complex K3[Fe(CN)6 ] is
    (a) potassium hexacyanoferrate (II)
    (b) potassium hexacyanoferrate (III)
    (c)potassium hexacyanoiron (II)
    (d) tripotassium hexacyanoiron (II)
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  27. Which among the followings is disaccharides
    (a) Glucose
    (b) cellulose
    (c) Sucrose
    (d) starch
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  28. Which among the followings is globular protein ?
    (a) Albumin
    (b) Keratin
    (c) collagen
    (d) None of the above
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  29. Which among the following is secondary amine:
    (a) CH3NH2
    (b) ( CH3)3N
    (c) CH3NHCH3
    (d) CH3CH2NH2
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  30. Alkyl cyanide upon reduction with Na/ethanol gives
    (a) Carboxylic acids
    (b) primary amines
    (c) sec- amine
    (d) tert-amine
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  31. Which among the followings is most acidic?
    (a) Acetic acid
    (b) Formic acid
    (c) Chloroacetic acid
    (d) Ethanol
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  32. Which among the followings undergoes cannizzaro’s reaction?
    (a) Ethanal
    (b) Benzaldehyde
    (c) Propanal
    (d) None of above
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  33. When alipahtic aldehydes are treate with fehling solution, following observation is obtained
    (a) White ppt
    (b) red coluration
    (c) Orange colouration
    (d) Brown coluration
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  34. In Clemmensen reduction the reducing agent used is
    (a) Na / ethanol
    (b) Zn-Hg /HCl
    (c) Mg-Hg/H2O
    (d) LiAlH4
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  35. One Faraday contains the charge
    (a) 95000C
    (b) 96500 C
    (c) 94500 C
    (d) 95600 C
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  36. XeF2 has linear structure because
    (a) Xe is sp3d2 hybridized having 6 bp and 1lp
    (b) Xe is sp3d2 hybridized having 4 bp and 2 lp
    (c) Xe is sp3d hybridized having 2 bp and 3 lp
    (d) Xe is sp3 hybridized having 3 bp and 1lp
    Very Short Answer 1 Marks Mar-2021 • PSEB Class 12th
  37. The vapour pressure of 2.1% of an queous solution pf a non electrolyte at 373 k is 755 mm calculate the molar mass of solute

    OR

    When 1.80 gm of non volatile compound is dissolved in 25 g of acetone, the solution boils at 56.86 C while pure acetone boils at 56.38 C under the same atmospheric pressure calculate the molar mass of the compound .Kb for acetone is 1.72 K kg mol-1
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  38. What is specific conductance of a solution ? How it varies with dilution ?
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  39. A first order reaction is found to have a rate constant k =5.5 X10-14 sec-1
    Find the half life period

    OR

    A first order reaction is 75% completed in 40 minutes , calculate its half life
    period
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  40. Why does NCl5 not exist ?
    OR
    Oxygen is a gas while sulphur is solid . explain
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  41. Why nitrous acid is oxidant as well as reductant ?
    OR
    What is the basicity of H3PO4 and why ?
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  42. Why transition metals act as good catalysts?
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  43. Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state?
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  44. What is meant by unidentate and ambidentate ligands? Give two examples for each.
    OR
    [Fe(CN)6]4–and [Fe(H2O)6]2+ are of different colours in dilute solutions. Why?
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  45. Explain the factors affecting rate of a reaction.
    Short Answer 2 Marks Mar-2021 • PSEB Class 12th
  46. Calculate the potential of hydrogen electrode in contact with a solution whose
    Long Answer 3 Marks Mar-2021 • PSEB Class 12th
  47. Compare and explain the reactivity OR different alcohols towards sodium.
    Long Answer 3 Marks Mar-2021 • PSEB Class 12th
  48. For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
    OR
    A first order reaction takes 40 min for 30% decomposition.
    Calculate half life period.
    Long Answer 3 Marks Mar-2021 • PSEB Class 12th
  49. Why is dioxygen a gas but sulphur a solid?
    Long Answer 3 Marks Mar-2021 • PSEB Class 12th
  50. Explain giving reasons-
    (i) Transition metals and many of their compounds show paramagnetic behav iour. (1)
    (ii) The enthalpies of atomisation of the transition metals are high. (2)
    (iii) The transition metals generally form coloured compounds. (2)

    OR

    (i) n-butyl chloride is treated with alcoholic KOH
    (ii) bromobenzene is treated with Mg in the presence of dry ether
    (iii) ethyl chloride is treated with aqueous KOHis act as good catalyst.(2)
    (iv) methyl bromide is treated with sodium in the presence of dry ether strongly oxidis
    (v) methyl chloride is treated with KCN ?
    (vi) The d' configuration is very unstable in ions.(1)
    Long Answer 5 Marks Mar-2021 • PSEB Class 12th

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01 How can I find PSEB 12th Chemistry previous year question papers for 1st semester on BRpaper?

Open the Chemistry subject page under PSEB 12th Class Question Papers and use it to browse available Chemistry previous year papers for 1st semester revision and board-style practice.

02 Can this Chemistry page help me understand the PSEB Class 12 paper pattern?

Yes. Students often use previous Chemistry papers on this page to review question style, section flow, recurring topic areas, and the overall structure seen in past Punjab board exams.

03 Are previous year Chemistry papers useful along with sample paper or model paper practice?

Yes. Previous year papers show real past exam style, while sample or model papers are commonly used for extra pattern-based practice. Using both can help with revision and time-based preparation.

04 Can I use past Chemistry papers to identify important questions and repeated topics?

Past papers are often used to spot commonly tested areas in Chemistry, such as numericals and questions from organic, inorganic, or physical chemistry. They are helpful for setting revision priorities, not for guaranteeing exact repeats.

05 Does this page include solved Chemistry papers or answer keys?

This subject page is mainly for browsing previous year Chemistry question papers. If solution-based practice is available anywhere on the site, students should verify it on the page instead of assuming all papers include answers.

06 How should I prepare for the Chemistry exam in limited time using previous papers?

Start by reviewing a few past Chemistry papers to understand the question pattern, then revise the chapters that appear frequently, practice numericals, and use the papers for timed self-testing before the exam.