ISC Class XII Board Examination
ISC Chemistry (Paper 1 — Theory) — Specimen Question Paper 2025
Specimen2025Subject code 862
- Board
- ISC Class XII Board Examination
- Class
- Class 12
- Subject
- Chemistry
- Year
- 2025
- Total marks
- Not verified
- Duration
- Not verified
Verification and rights
Checked against a named, citable source that is recorded with the record.
Imported specimen paper from CollegeDekho (mirror of CISCE PDF) on 2026-08-29.
Questions in this paper
Section A
- 1((i))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
The molar conductance of a solution _________ on dilution but the
specific conductance of a solution _________ on dilution. - 1((ii))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
In the complex ion [CoCl(en)2ONO]+, the coordination number and
the oxidation number of the central metal ion are ______ and
________. - 1((iii))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
Propanone on reaction with zinc amalgam in the presence of
concentrated HCl gives ______ and the reaction is called _______
reduction. - 1((iv))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
The variation and magnitude of oxidation state in coordination
complexes is due to the participation of inner ________ electrons in
addition to outer __________ electrons.
(B) Select and write the correct alternative from the choices given below. [7×1] - 1((i) [Section A])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
The correct order of the increasing basic nature of Ammonia,
Methylamine and Aniline is: - 1((ii) [Section A])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
Colligative properties of a solution are:
(P) Independent of the nature of solute
(Q) Proportional to molecular mass of solute
(R) Proportional to concentration of solute
(S) Independent of the amount of solvent - 1((iii) [Section A])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
According to Markownikoff’s rule, “The negative part of the halogen acid
attaches itself with that C atom of an unsymmetrical alkene which has least
number of H-atom.”
Anti-Markownikoff’s addition of HBr is NOT observed in: - 1((vi))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
Given below are two statements marked Assertion and Reason. Read the two
statements carefully and select the correct option.
Assertion: Tertiary butyl bromide undergoes Wurtz reaction to give 2,2,3,3
tetramethyl butane.
Reason: In Wurtz reaction, when same alkyl halides react with sodium in dry
ether to give hydrocarbon; the hydrocarbon formed contains double
the number of carbon atoms present in the alkyl halide. - 1((vii))(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
Given below are two statements marked Assertion and Reason. Read the two
statements carefully and select the correct option.
Assertion: There is a continuous increase in size among Lanthanoids with an
increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction. - 1((i) [Section A 2])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
Write the relation between the decay constant and half-life period. - 1((ii) [Section A 2])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
In a piece of dead wood, the activity or concentration of C-14 is found
to be one third of its initial activity. Calculate the age of the old wood. - 1((iii) [Section A 2])(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1] brackets: [four, three, remains same, propane, ns1-2, increases, six, propan-2-ol, (n-1)d1-10, two, decreases, Clemmensen’s, Wolff-Kishner]
The half-life period (t1/2) for a first order reaction is 30 minutes.
Calculate the time taken to complete 87·5% of the reaction.
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Section B
- 9((i))Identify the compounds [A] and [B ] in the following reactions.
(1) K2Cr2O7/H2SO4 C6H6(anhy. AlCl3)
(a) C6H5CHO [A] [B]
(2) SOCl2
(1) H2SO4/HgSO4 C2H5OH
CH3-C≡CH [A] [B]
(b) (2) vigorous oxidation, [conc. H2SO4]
conc.HNO3
OR - 9((ii))Three organic compounds A, B and C are non cyclic functional isomers of
carbonyl compounds with molecular formula C4H8O. Isomers A and C give
positive Tollen’s test while compound B does not give positive Tollen’s test but
gives positive iodoform test. Compounds A and B on reduction with Zn amalgam
and conc. HCl give the same product.
(a) Write the structures of the compounds A, B and C.
(b) Out of the compounds A, B and C, which one will be the least reactive
towards addition of HCN.
Section C
- 12((i))3] Identify the compounds [A], [B] and [C] in the following reactions. 6[H] HNO2 + HCl C6H5NH2
C6H5NO2 [A] [B] [C]
Sn/HCl 273K-278K
(1) HNO2 (1) KCN (1) NH3/heat - 12((ii))3] Identify the compounds [A], [B] and [C] in the following reactions. 6[H] HNO2 + HCl C6H5NH2
CH3CH2NH2 [A] [B] [C]
(2) P/Cl2 (2) H2O/H+ (2) Br2/KOH - 13((i))Calculate the abnormal molecular mass of solute in both the cases.
- 13((ii))Inferring the value of van’t Hoff factor in both the cases, find out which
solution undergoes association and which solution undergoes
dissociation. - 13((iii))Given below is the increasing order of depression in freezing point of
water observed for equimolar concentrations of the compounds,
acetic acid < trichloro acetic acid < trifluoro acetic acid
Provide a reason to explain if the above ordered arrangement is correct or
not. - 15((i))Assuming that cyanide is a strong ligand, write the formula of two coordination
complex ions with cyanide and iron having coordination number six. Name the
complex ions. - 15((ii))On the basis of Crystal Field Theory, write the electronic configuration of d4 ion
if:
(a) ∆o > P
(b) ∆o< P - 16((i))Dry cells are commonly used in clocks, torches, calculators etc. They are the
most familiar type of commercial cells.
(a) What acts as anode and cathode in dry cell?
(b) Which chemical compounds are filled between anode and cathode of this
cell?
(c) Why do dry cells not have a long life?
OR - 16((ii))Answer the following:
(a) What happens to the voltage when the salt bridge is removed from the two
half cells and why?
(b) Copper sulphate solution cannot be stored in a zinc pot. Why?
(c) Why does the density of H2SO4 in a lead storage battery decrease as it is
discharged? - 17((i))The structures of glycine and alanine are given below. Show the peptide bond
linkage in glycylalanine.
CH3
H2N-CH2-COOH H2N-CH-COOH
Glycine Alanine - 17((ii))What products would be formed when a nucleotide from DNA containing
thymine is hydrolysed? - 17((iii))What are reducing sugars? Give an example.
---------------------------------------------------------------------------------------------------------------- - 18((i))3] Consider the data given below for the reaction A + B Product S.No. conc. of [A] mol L-1 conc. of [B] mol L-1 Rate; mol L-1sec-1 1. 0·1 0·1 4·0 × 10- 4 2. 0·2 0·2 1·6 × 10- 3 3. 0·5 0·1 1·0 × 10- 2 4. 0·5 0·5 1·0 × 10- 2 Answer the following questions.
What is the order of reaction with respect to A and B? - 18((iii))3] Consider the data given below for the reaction A + B Product S.No. conc. of [A] mol L-1 conc. of [B] mol L-1 Rate; mol L-1sec-1 1. 0·1 0·1 4·0 × 10- 4 2. 0·2 0·2 1·6 × 10- 3 3. 0·5 0·1 1·0 × 10- 2 4. 0·5 0·5 1·0 × 10- 2 Answer the following questions.
Determine the reaction rate when the concentration of A and B are
0·2 mol L-1sec-1 and 0·35 mol L-1sec-1 respectively.
Section D
- 19((i))Write the chemical equation for the preparation of phenol from benzene using
H2SO4 and NaOH. - 19((ii))What happens when phenol reacts with Br2/CS2 at low temperature?
- 19((iii))What is observed when phenol is treated with neutral ferric chloride solution?
- 19((iv))Write the reaction when phenol is treated with conc. HNO3 in the presence of
conc. H2SO4. - 19((v))Write the reaction when phenol is treated with chloroform in the presence of
aqueous NaOH at 340K.
---------------------------------------------------------------------------------------------------------------- - 20((i))Give a reason for each of the following.
(a) The purple colour of KMnO4 disappears in the presence of acidified
solution of oxalic acid.
(b) Some transition metals and their compounds get attracted towards the
magnetic field.
(c) 2+ 2+
Why are Mn compounds more stable than Fe towards oxidation to the
+3 state? (atomic no. of Mn = 25 and Fe = 26) - 20((ii))Complete and balance the following reactions.
(a) KMnO4 + H2SO4 + FeSO4 → ______+ ______+_____+______
(b) K2Cr2O7 + H2SO4 + KI → ______+ ______+_____+______ - 21((i))Osmosis and osmotic pressure play a very significant role in biological processes.
The osmotic pressure of human blood is 8·21 atm at 27oC. It is interesting to know
that a 0·91% (mass/volume) solution of NaCl, known as saline water is isotonic
with fluids inside the human red blood cells. In this solution, the blood corpuscles
neither swell nor shrink. Therefore, medicines are mixed with saline water before
being injected into the veins.
Answer the following questions. - 21((ii))(a) Calculate the boiling point of urea solution when 8·0g of urea is dissolved
in 250g of water. Boiling point of pure water is 373K.
(kb of water = 0·52 K kg mol-1, molecular mass of urea = 60 g mol-1)
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(b) Ethylene glycol is used as an antifreeze agent. Calculate the amount of
ethylene glycol to be added to four kilogram of water to prevent it from
freezing at -6oC.
(Kf of water = 1·86 K kg mol-1) Assume that ethylene glycol
(CH2OH.CH2OH) does not dissociate or associate in aqueous solution.
(c) What will be the effect on the value of molality and molarity of a solution
with change in temperature?
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CHEMISTRY