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Chemistry · Class 11 Science

Assam Ahsec Class 11 Chemistry — Real Previous-Year Papers

with complete answers

Real previous-year board papers, year by year — the official exam pattern, the full question paper, and every question solved the concept-first way. Distinct from the chapter-wise textbook bank.

2018–2026
Years of papers
8
Total Papers
8
Real Board Papers
0
Sample papers
357
Real-paper Q & A
0
Sample-paper Q & A

Real board-paper questions available, by year

—2026Paper not yet available
52 Q2025complete
45 Q2024complete
45 Q2023complete
45 Q2022complete
—2021Exam cancelled (COVID-19)
37 Q2020complete
34 Q2019complete
40 Q2018complete

2026 — Paper not yet available: The AHSEC HS 1st Year exam was presumably held this year, but no verified question paper for this subject has been found from the sources we check. We publish only a paper we can verify against a real printed original — it will appear here once it is.

2021 — Exam cancelled (COVID-19): AHSEC cancelled the HS 1st Year (Class-11) examination in 2021 due to COVID-19; an order dated 7 May 2021 promoted all registered students to HS 2nd Year without sitting it. No annual question paper was conducted or printed that year, so none exists to publish.

AHSEC Higher Secondary (HS) 1st Year Examination 2026 · Set ANNUAL

Real board examination

About this paper

The real Class-12 board examination held in 2026. Every question below is solved the concept-first way. Sample papers are labelled honestly — never shown as a past exam.

Total marks
—
Questions
—
Duration
—
Sections
—

The marks / questions / duration above are the official exam pattern. We currently have 59 of this paper’s questions, with 59 fully solved. Questions we couldn’t yet extract or verify are held — never shown as complete.

The question paper

The questions we hold for this paper, laid out by section. Solutions are on the Answers tab.

Board Examination

Chemistry

AHSEC Higher Secondary (HS) 1st Year Examination 2026 · Set ANNUAL

Series/Set: ANNUALRoll No. ________
Time Allowed: —Maximum Marks: —
Section A

Q1.
The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following elements contains the greatest number of atoms?
  • (a) 4 g He
  • (b) 46 g Na
  • (c) 0.40 g Ca
  • (d) 12 g He
[1]
Q2.
One mole of oxygen gas at STP is equal to _____.
  • (a) 6.022 x 10^22 molecules of oxygen
  • (b) 6.022 x 10^23 atoms of oxygen
  • (c) 16 g of oxygen
  • (d) 32 g of oxygen
[1]
Q3.
One of the statements of Dalton's atomic theory is given below: "Compounds are formed when atoms of different elements combine in a fixed ratio". Which of the following laws is not related to this statement?
  • (a) Law of conservation of mass
  • (b) Law of definite proportions
  • (c) Law of multiple proportions
  • (d) Avogadro law
[1]
Q4.
Which of the following orbitals has dumb-bell shape?
  • (a) s
  • (b) p
  • (c) d
  • (d) f
[1]
Q5.
The correct order of increasing energy of atomic orbital is
  • (a) 5p<4f<6s<5d
  • (b) 5p<6s<4f<5d
  • (c) 4f<5p<5d<6s
  • (d) 5p<5d<4f<6s
[1]
Q6.
Quantum numbers n=2, l=1 represent :
  • (a) 1s orbital
  • (b) 2s orbital
  • (c) 2p orbital
  • (d) 3d orbital
[1]
Page 1 of 8
Q7.
Which of the following is responsible to rule out the existence of definite paths or trajectories of electrons? (a) Pauli's exclusion principle (b) Heisenberg's uncertainty principle (c) Hund's rule of maximum multiplicity (d) Aufbau principle
[1]
Q8.
The increasing order of effective nuclear charge in Na, Al, Mg and Si atoms (a) Na < Mg < Si < Al (b) Na < Mg < Al < Si (c) Mg < Na < Al < Si (d) Na = Mg = Al = Si
[1]
Q9.
The correct order of first ionization potential among following elements, Be, B, C, N and O is: (a) B < Be < C < O < N (b) B < Be < C < N < O (c) Be < B < C < N < O (d) Be < B < C < O < N
[1]
Q10.
Which of the following has the smallest radius? (a) Sn4+ (b) Li+ (c) Ca2+ (d) Al3+
[1]
Q11.
Find the molecule in which the central atom is having one lone pair of electrons (a) NH3 (b) PCl5 (c) H2O (d) CH4
[1]
Q12.
During change of O2 to O2^- ion, the electron adds on which of the following orbitals? (a) sigma* orbital (b) pi orbital (c) sigma orbital (d) pi* orbital
[1]
Q13.
What is the molecular geometry of SF6 as predicted by VSEPR theory? (a) Square planar (b) Octahedral (c) Trigonal bipyramidal (d) Tetrahedral
[1]
Q14.
The open system allows the transfer of ___. (a) Only mass (b) only energy (c) both mass and energy (d) neither mass and energy
[1]
Q15.
Which of the following relation is true between Gibbs energy, enthalpy, temperature and entropy? (a) G=H-TS (b) G=H-T (c) G=H-S (d) G=-TS
[1]
Q16.
Which of the following is not correct? (a) delta-G is zero for a reversible reaction (b) delta-G is positive for a spontaneous reaction (c) delta-G is negative for a spontaneous reaction (d) delta-G is positive for a non-spontaneous reaction
[1]
Page 2 of 8
Q17.
Which of the following is an extensive property? (a) Molar heat capacity (b) temperature (c) enthalpy (d) all of these
[1]
Q18.
When work is done on a system or by a system there is a change in ___. (a) external energy (b) internal energy (c) adiabatic energy (d) isothermal energy
[1]
Q19.
A weak electrolyte is characterized by : (a) Complete ionization in solution (b) Partial ionization in solution (c) No ionization in solution (d) High electrical conductivity
[1]
Q20.
The concentration of hydrogen ion in a sample of soft drink is 3.8 x 10^-3 M. What is its pH? (a) 1.37 (b) 2.42 (c) 3.34 (d) 4.56
[1]
Q21.
What is the pH of a buffer solution prepared from 0.1 M acetic acid and 0.1 M sodium acetate? (Given pKa of acetic acid = 4.76) (a) 4.76 (b) 7.00 (c) 3.76 (d) 5.76
[1]
Q22.
Consider the reaction: Zn + Cu2+ -> Zn2+ + Cu; With reference to the above, which one of the following is the correct statement? (a) Zn is reduced to Zn2+ ions. (b) Zn is oxidised to Zn2+ ions. (c) Zn2+ ions are oxidised to Zn. (d) Cu2+ ions are oxidized to Cu.
[1]
Q23.
Oxidation number of P in PO4³-, of S in SO4²- and that of Cr in Cr2O7²- are respectively : (a) +3, +6 and +5 (b) +5, +3 and +6 (c) +3, +6 and +6 (d) +5, +6 and +6
[1]
Q24.
The structure of 4-Methylpent-2-en-1-ol is : (a) CH3CH2CH=CHCH2OH (b) (CH3)2C=CHCH2CH2OH (c) (CH3)2CHCH=CHCH2OH (d) CH3CH(OH)CH-CH=C(CH3)2
[1]
Q25.
The principle involved in paper chromatography is : (i) Adsorption (ii) Partition (iii) Solubility (iv) Volatility
[1]
Q26.
The increasing order of electron donating inductive effect of alkyl group is : (a) -H < -CH3 < -C2H5 < -C3H7 (b) -H > -CH3 > -C2H5 > -C3H7 (c) -H < -C2H5 < -CH3 < -C3H7 (d) -H > -C2H5 > -CH3 > -C3H7
[1]
Page 3 of 8
Q27.
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
[1]
Q28.
During Lassaigne's test set of Sulphur and nitrogen present in an organic compound change into: (a) Na2S and NaCN (b) Na2SO4 and NaCN (c) Na2S and NaCNO (d) NaCN and NaCNO
[1]
Q29.
A miscible mixture of benzene and chloroform can be separated by: (a) Sublimation (b) distillation (c) filtration (d) crystallisation
[1]
Q30.
Which of the following conformation of n-butane is the most stable? (a) eclipsed (b) gauche (c) staggered (d) skew boat
[1]
Q31.
Find the correct order for the ease of formation of free radicals: (a) 1° > 2° > 3° (b) 3° > 2° > 1° (c) 2° > 1° > 3° (d) 2° > 3° > 1°
[1]
Q32.
Formation of an alkane from the reduction of an alkyl halide with Zn is known as (a) Cannizzaro reaction (b) Frankland reaction (c) Kolbe's reaction (d) Wurtz reaction
[1]
Q33.
Which of the following will not undergo Friedel-Craft's reaction readily? (a) Toluene (b) Xylene (c) Cumene (d) Nitrobenzene
[1]
Q34.
Benzene reacts with CH3Cl in the presence of anhydrous AlCl3 to form (a) Chlorobenzene (b) Benzyl chloride (c) xylene (d) toluene
[1]
Q35.
The addition of ozone to an alkene 'X' to form ozonide and then cleavage of ozonide by Zn-H2O to form pentan-3-one and methanal. The alkene 'X' is (a) Pent-2-ene (b) Hex-3-ene (c) 2-Ethylbut-1-ene (d) 2-Ethylpent-1-ene
[1]
Page 4 of 8
Section B

Q1.
The density of 3 molal solution of NaOH is 1.110 g mL^-1. Calculate the molarity of the solution.
[2]
Q2.
What is the physical significance of Psi²?
[2]
Q3.
What is the basic difference between the term electron gain enthalpy and electronegativity?
[2]
Q4.
N2 is diamagnetic while O2 is paramagnetic. Explain on the basis of Molecular orbital theory.
[2]
Q5.
In a process, 701 J of heat is absorbed by a system and 394 J of work is done by the system. What is the change in the internal energy for the process?
[2]
Q6.
Predict the products of electrolysis in each of the following: (i) An aqueous solution of AgNO3 with silver electrodes. (ii) An aqueous solution of silver nitrate with platinum electrodes.
[2]
Q7.
Draw the resonance structures for the following compounds. Show the electron shift using curved-arrow notation. (i) C6H5OH (ii) CH3NO2
[2]
Q8.
Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example.
[2]
Page 5 of 8
Q9.
The molar mass and empirical formula of a compound are 180 g and CH2O respectively. What will be its molecular formula?
[2]
Q10.
Among the following pairs of orbitals, which orbital will experience more effective nuclear charge: (i) 2s and 3s (ii) 3d and 3p?
[2]
Q11.
How would you explain the fact that first ionization enthalpy of sodium is lower than Mg but its second ionization enthalpy is higher than that of Mg?
[2]
Q12.
How do atomic radii vary in a group and a period?
[2]
Q13.
Neither q nor w is a state function but (q + w) is a state function. Explain.
[2]
Q14.
Use the Henderson-Hasselbalch equation to determine the pH of a buffer solution containing 0.05 M NH4OH and 0.1 M NH4Cl. (pKb of NH4OH = 4.75)
[2]
Q15.
(i) Will CCl4 give white ppt of AgCl on heating with silver Nitrate? Give reason for your answer. (ii) Define hyper conjugation.
[2]
Q16.
Which of the following compounds are aromatic according to Huckel's rule? (i) naphthalene (ii) pyrrole (iii) cyclobutadiene (iv) 1,2-dihydronaphthalene
[2]
Page 6 of 8
Q17.
An atom of an element contains 29 electrons and 35 neutrons. Deduce (i) the number of protons (ii) the electronic configuration of the element (iii) Identify the element.
[3]
Q18.
Using Aufbau principle, write the ground state electronic configuration of following atoms. (i) Boron (Z = 5) (ii) Neon (Z = 10) (iii) Aluminium (Z = 13) (iv) Chlorine (Z = 17)
[3]
Q19.
Why dipole moment of BF3 is zero but for PCl3 it is non zero?
[3]
Q20.
At the temperature 298 K, the Kp of the reaction is given as N2O4 (g) <=> 2NO2 (g) is 0.98. Predict whether the reaction is spontaneous or not.
[3]
Q21.
What is pH? Calculate the degree of hydrolysis, hydrolysis constant and pH of 0.10 M NH4Cl solution. Given that Kb = 1.8 x 10^-5.
[3]
Q22.
Distinguish between inductive effect and resonance effect. Give the number of sigma and pi bond in the following molecule HCONHCH3.
[3]
Q23.
Draw Newman and Sawhorse projections for the eclipsed and staggered conformations of ethane. Which of these conformations is more stable and why?
[3]
Page 7 of 8
Q24.
Complete the following reactions: (i) Cyclobutanecarbonitrile (cyclobutane bearing a -CN group) treated with H2/Ni. (ii) 2-Methylbenzenediazonium chloride bearing an ortho -Br substituent (ring with -CH3, an adjacent -Br, and a -N2+Cl- diazonium group) treated with H3PO2/H2O. (iii) Benzylamine (C6H5CH2-NH2) + CHCl3 with Ethanolic KOH.
[3]
Page 8 of 8