Class 12 PT II Question Paper 2025-26 Chemistry

CBSE CLASS 12
PT II Question Paper
Session 2025-26

CHEMISTRY

Exam CBSE Class 12
Subject Chemistry
Session 2025-26
Document Type PT II Question Paper

Notes · Sample Papers · Previous Year Papers · Mock Tests

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Question Paper
SECOND UNIT TEST
SESSION: 2025 – 2026 ag
CLASS: XII MAXIMUM MARKS: 40
SUBJECT: CHEMISTRY TIME: 1 HOUR 30 MINUTES
GENERAL INSTRUCTIONS:
Read the following instructions carefully and follow them:
1.� This question paper contains18 questions. All questions are compulsory.

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2.� This question paper is divided into five sections – Section A, B, C, D and E

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3.� SECTION A – Question number 1 to 8 are multiple choice questions. Each question carries 1 mark.
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4.� SECTION B – Question number 9 to 11 are very short answer type questions. Each question carries

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2 marks.

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5.� SECTION C – Question number 12 to 15 are short answer type questions. Each question carries 3
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marks.

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6.� SECTION D – Question number 16 is case-based question and carries 4 marks.
7.� SECTION E – Question number 17 and 18 are long answer type questions. Each question carries 5
marks.
8.� There is no overall choice given in the question paper. However, an internal choice has been
provided in few questions in all the sections except section A and B.
9.� Use of log tables and calculator is not allowed.

SECTION – A
Select and write the most appropriate option out of the four options given for each of the

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questions 1 - 8.
1. Study the graph carefully and match the column I with column II and select the correct option 1

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using the codes given below:

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Column II
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(i) -10kj

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q. Ea(backward) (ii) 40kj

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(iii) 30kj
(iv) 50kj
Answer codes:
p q r s
(A) (iv) (ii) (iii) (i)
(B) (iii) (iv) (i) (ii)
(C) (iii) (ii) (i) (iv)
(D) (iv) (iii) (ii) (i)

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2. The rate of reaction is expressed in different ways as follows: 1

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The reaction is
(A) 2C + 3D  4A + B (B) 4A + 2CB + 3D
(C) B + D A + C (D) B + 3D 4A + 2C
3. When KMnO4 solution is added to oxalic acid solution, the decolourisation is slow in the 1
beginning but becomes instantaneous after some time, Identify the most appropriate statement
about the above activity.
(A) CO2 is formed as the product. (B) Reaction is exothermic
(C) MnO4- catalyses the reaction (D) Mn2+ acts as auto-catalyst.
4. In the complex compound Fe4[Fe(CN)6]3 oxidation states of counterion Fe and central metal ion 1
Fe, respectively, are:
(A) +2, +3 (B)+3, +2 (C) +4, +3 (D) +2, +2
5. The correct statement with respect to the complex Ni(CO)4 and [Ni(CN)4]2- is 1
(A) Both have tetrahedral geometry.
(B) Both have square planar geometry.
(C) Have square planar and tetrahedral geometry respectively.
(D) Have tetrahedral and square planar geometry respectively.
6. The decreasing order of basicity of the following amines is- 1

(A) (II) > (I )> (III) > (IV) (B) (I) > (II) > (III) > (IV)
(C) (II) > (I) > (IV)> (III) (D) (I) > (II) > (IV) > (III)
Note: For question number 7 & 8 two statements are given – one labelled as Assertion (A)
and the other labelled as Reason (R). Select the correct answer to these questions from the
codes (A), (B), (C) and (D) as given below.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true but R is not the correct explanation of A
(C) A is true but R is false
(D) A is false and R is true
7. Assertion (A): For a certain reaction, a large fraction of molecules has energy more than 1
threshold energy, still the rate of reaction is very slow.
Reason (R): The colliding molecules must not be properly oriented for effective collisions.
8. Assertion (A): Lanthanoids show a limited number of oxidation states whereas actinoids show 1
a large number of oxidation states.
Reason (R): Energy gap between 4f, 5d and 6s subshells is small whereas that in between 5f,
6d and 7s subshells is large.
SECTION – B
Questions 9 to 11 are very short answer questions carrying 2 marks each.
9. The rate constant for a first order reaction is 60 s-1. How much time will it take to reduce the 2
initial concentration of the reactant to 1/16 th of its initial value? (log2=0.3010)
10. A coordination compound CoCl3. 4H2O precipitates silver chloride when treated with silver 2
nitrate. The molar conductance of its solution corresponds to a total of two ions. Write
structural formula of the compound and name it.
11. Account for the following: 2
(a) Acetylation of aniline reduces its activation effect.
(b) Although –NH2 group is o/p directing, yet aniline on nitration gives a significant amount of
m-nitroaniline.

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SECTION – C

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Questions numbers 12 to 15 are short questions carrying 3 marks each.
12. Give reason for the following: 3
(a) Zn, Cd and Hg are soft and have low melting point.
(b) Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
(c) La(OH)3 is more basic than Lu(OH)3.
13. (a) Write the formula of the following coordination compound: 3
pentaamminecarbonatocobalt(III) chloride.
(b) Draw the structure of geometrical and optical isomer of [Pt(en)2Cl2]2+.
(c) FeSO4 solution mixed with (NH4)2SO4 solution in 1:1 molar ratio gives the test of Fe2+ ion

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but CuSO4 solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test

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of Cu2+ ion. Explain why?

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14. (a) Does ionization isomer for the following compound exist? Justify your answer.

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(b) Out of [CoF6]3- and [Co(en)3]3+ which complex is more stable and why?
(c) On the basis of crystal field theory, write the electronic configuration of d6 ion in an
octahedral field when ∆0<P.
OR 3
(a) CO is more complexing reagent than NH3. Explain.
(b) Explain [Co(NH3)6]3+ is an inner orbital complex whereas [Ni(NH3)6]2+ is an outer orbital
complex.
(c) Arrange the following complex ions in increasing order crystal field splitting energy (∆0);
[CrCl6]3- , [Cr(CN)6]3- , [Cr(NH3)6]3+.

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15. A compound ‘A’(C3H7NO) on reaction with Br2 and KOH gives ‘B’. ‘B’ on reaction with
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CHCl3 and KOH gives ‘C’. ‘B’ reacts with Hinsberg’s reagent to form ‘D’ which is soluble in
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KOH. Identify A to D. Write the reaction involved in the step from ‘B’ to ‘D’.

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l based question carrying 4(2+1+1) marks.
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Section

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Questions numbers 16 is case
16. Read the passage given below and answer the following questions: 4
Amines can be considered as derivatives of ammonia, obtained by replacement of one, two or
all the three hydrogen atoms by alkyl or aryl groups. They are usually prepared from nitro
compounds, halides, amides, imides etc. They exhibit hydrogen bonding which influence their
physical properties. In alkyl amines, a combination of inductive effect, steric effect and
hydrogen bonding factors influence the stability of the substituted ammonium cations in protic
polar solvents and thus affect the basic nature of amines. In aromatic amines, electron releasing

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and withdrawing groups, respectively increase and decrease the basic character. Influence of

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the number of hydrogen atoms at nitrogen atom on the type of reactions and nature of products

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is responsible for identification and distinction between primary, secondary and tertiary amines.

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Presence of amino group in aromatic ring enhances reactivity of aromatic amines. Aryl

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diazonium salts provide advantageous methods for producing aryl halides, cyanides, phenols,

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arenes by reductive removal of diazo group.

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Answer the following questions:
(a) Complete the following reactions giving main products:

(b) What type of compounds are formed in coupling reactions?

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(c) Out of primary amines and tertiary amines which one has higher boiling point and why?

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OR

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(c) Aniline does not undergo Friedel- Crafts reaction. Explain.

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Section E
Questions numbers 17 and18 are long answer type questions carrying 5 marks each.
17. Explain the following: 5
(a)Transition elements exhibit higher enthalpies of atomisation.
(b) Cr2+ reducing and Mn3+ oxidising when both have d4 configuration.
(c) MnO is basic but Mn2O7 is acidic.
(d) The transition metals and their compounds are known for their catalytic activity.
(e) Zirconium (Zr) and hafnium (Hf) have nearly identical atomic radii.
OR
(a) When FeCr2O4 is fused with Na2CO3 in the presence of air, it gives a yellow solution of 5
compound (A). Compound (A) on acidification gives compound (B). Compound (B) on
reaction with KCl forms an orange colour compound (C). An acidified solution of compound
(C) oxidises Na2SO3 to (D). Identify (A) , (B) , (C) and (D).
(b) How does (i) acidified permanganate solution react with nitrite (NO-2) ion?
(ii) alkaline solution of permangate solution react with iodide (I-) ion?
(c) What happens when KMnO4 is heated (at 513K)?
18. A. (a) Draw the plot of lnk vs 1/T for a chemical reaction. What does the intercept represent 5
What is the relation between slope and Ea? (k = rate constant, T = absolute temperature)
(b) A first order reaction takes 30 minutes for 20% decomposition. Calculate t1/2?
[log2 = 0.301]
B. For a reaction A + B  P, the rate is given by
Rate= k[A][B]2
a) How is the rate of reaction affected if the concentration of B is doubled?
b) What is the overall order of reaction if A is present in large excess?
OR
A. Observe the graph shown in figure and answer the following questions. 5

(a) Predict the order of the reaction?
(b)What is the slope of the curve?
(c)Write the relationship between k and t½ (Half -life period).
B. For a homogeneous gas phase reaction A(g)  B(g) + C(g) + D(g), the pressure of the
reaction mixture increases by 40% in 20 minutes. Calculate rate constant of a reaction.

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