Kerala Plus Two Question Paper 2025 Chemistry

KERALA BOARD

QUESTION
PAPER
2025
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Kerala Board of Public
Examinations

SY-425
Reg. No. : ......................................

Name : ...........................................

SECOND YEAR HIGHER SECONDARY EXAMINATION, MARCH 2025

Part – III Time : 2 Hours
CHEMISTRY Cool-off time : 15 Minutes
Maximum : 60 Scores

General Instructions to Candidates :
 There is a ‘Cool-off time’ of 15 minutes in addition to the writing time.
 Use the ‘Cool-off time’ to get familiar with questions and to plan your answers.
 Read questions carefully before answering.
 Read the instructions carefully.
 Calculations, figures and graphs should be shown in the answer sheet itself.
 Malayalam version of the questions is also provided.
 Give equations wherever necessary.
 Electronic devices except non-programmable calculators are not allowed in the
Examination Hall.

 
    15  ‘  ’ .
 ‘  ’    
 .
      .
    .
  , , ,   
.
   .
    .
     
    .

SY-425 1 P.T.O.

Answer any 4 questions from 1 to 5. Each carries 1 score. (4  1 = 4)
1. Dissolution of a gas in liquid is a process
(a) with increase in enthalpy
(b) with no change in enthalpy
(c) with decrease in enthalpy
(d) for which enthalpy change cannot be predicted

2. For a reaction, a plot between concentration of reactant, [R] and time, t is as shown
below :

The order of the reaction is _____ .

3. The transition element present in ‘bronze’ is _____ .

4. Identify the product formed by the catalytic reduction of propanal.

5. The zwitter ion of the amino acid, H2N – CH2 – COOH is _____ .

Answer any 8 questions from 6 to 15. Each carries 2 scores. (8  2 = 16)
6. Find the relative lowering of vapour pressure of the solution containing 0.5 mol
glucose dissolved in 55.5 mol of water.

7. Write the cell representation for the determination of standard electrode potential of
Cu2+/Cu electrode using ‘SHE’.

SY-425 2

1  5    4  .
1  . (4  1 = 4)
1.     
(a)  
(b)  
(c)  
(d)    .

2.     , [R]; , t
     :

   ___________ .

3.       _________
.

4.     
  .

5. H2N – CH2 – COOH     _____ .

6  15    8  .
2  . (8  2 = 16)
6. 0.5  , 55.5     
   .

7. ‘SHE’  Cu2+/Cu    
    .

SY-425 3 P.T.O.

8. Derive an expression for half-life of a first order reaction from its integrated rate
equation.

9. Define collision frequency and effective collisions on the basis of collision theory.

10. Classify the following compounds into allylic, benzylic, vinylic and aryl halides :

(A) (B)

(C) (D)

11. Write the IUPAC names of the major products in the reactions given below :

(i) Acid catalysed hydration of propene. (1)
(ii) Addition of CH3MgBr on HCHO followed by hydrolysis. (1)

12. Reaction of phenol with NaOH indicates the acidic nature of phenol.

(i) Write the chemical equation representing the reaction of phenol with NaOH. (1)

(ii) Give reason for the acidic nature of phenol. (1)

13. Write the chemical equations for :

(i) reaction of with bromine water. (1)

(ii) reaction of (CH3) C – O – CH3 with HI. (1)
3

14. How is an alkanenitrile, converted into a ketone ?

SY-425 4

8.     
      
.

9.   , ‘ ’, ‘
’  .

10.     , 
,  ,    
 :

(A) (B)

(C) (D)

11.      
 IUPAC   :
(i)      . (1)
(ii) HCHO- CH3MgBr    . (1)

12. , NaOH-  ,   
.
(i) , NaOH-    
 . (1)
(ii)      . (1)

13.     . :

(i) ,      . (1)

(ii) (CH3) C – O – CH3, HI   . (1)
3

14. ‘ ’    ?

SY-425 5 P.T.O.

15. Write the chemical reaction representing the preparation of CH3CH2NH2, starting

from (potassium phthalimide).

Answer any 8 questions from 16 to 26. Each carries 3 scores. (8  3 = 24)

16. (i) A solution of ethanol and water shows positive deviation. Why ? (1)

(ii) Represent graphically, the positive and negative deviations shown by non-ideal
solutions. (2)

17. Calculate the electrode potential of hydrogen electrode in contact with 0.01 molar H +
ion solution.
([H2] = 1, E H+/H = 0 V)
2

18. For the reaction, 2NO(g) + O2(g)  2NO2(g), experiments show that the rate,
r  [NO]2 and r  [O2]. If so,

(i) Formulate rate equation for it. (1)

(ii) Give its order and molecularity. (1)

(iii) If [NO] is increased three times the initial value, what happens to its rate ? (1)

19. Account for the following :

(i) Scandium (Z = 21) is a transition element but zinc (Z = 30) is not. (1)

(ii) Transition elements exhibit high enthalpies of atomisation. (1)

(iii) Mn3+ shows oxidising property. (1)

20. Briefly explain lanthanoid contraction, its cause and consequences.

SY-425 6

15. ( )   

, CH3CH2NH2    
 .

16  26    8  .
3  . (8  3 = 24)
16. (i)      
.  . (1)
(ii)     , 
   . (2)

17. 0.01  H+    
   .
([H2] = 1, E H+/H = 0 V)
2

18. 2NO(g) + O2(g)  2NO2(g) ,  , , r  [NO]2
 r  [O2]  ,
(i)    . (1)
(ii) ,   . (1)
(iii) [NO]       
  ? (1)

19.     :
(i)  (Z = 21)   ,   (Z = 30)
 . (1)
(ii)      
. (1)
(iii) Mn3+  . (1)

20.  ,  ,   
.

SY-425 7 P.T.O.

21. A compound with molecular formula, PtCl2∙2NH3 gives no precipitate, when treated
with excess AgNO3. If so,

(i) Write the primary and secondary valences of Pt in the compound. (1)
(ii) Give the IUPAC name of the coordination compound corresponding to the
above formula. (1)
(iii) Represent the configurations of geometrical isomers of the above co-ordination
compound. (1)

22. Write any three limitations of Valence Bond Theory to explain the bonding in co-
ordination compounds.

23. Observe the given chemical reactions and answer the questions followed :
I. A + SOCl2  CH3CH2Cl + SO2 + HCl
B
II. CH3CH2Cl  CH3CH2I
acetone
alc.KOH
III. CH3CH2Cl  C

(i) Identify A, B and C (1)
(ii) Write the name of the reaction II. (1)
(iii) In reaction III, if we use aqueous KOH, instead of alcoholic KOH, what will be
the product ? (1)

24. (i) Explain, why aldehydes are generally more reactive than ketones in nucleophilic
addition reactions. (2)
(ii) Write the chemical equation representing the addition of HCN on CH 3CHO. (1)

25. (i) Aniline is less basic than ammonia. Why ? (1)
(ii) How, aniline is converted into 4-bromo aniline ? (2)

26. Briefly explain the classification of carbohydrates, on the basis of their behaviour on
hydrolysis, with suitable examples.

SY-425 8

21. PtCl2∙2NH3    ,   AgNO3
   . 
(i)  , Pt  ,  
. (1)
(ii)    IUPAC  . (1)
(iii)     
 . (1)

22.     ‘
 ’   .

23.      
 :
I. A + SOCl2  CH3CH2Cl + SO2 + HCl
B
II. CH3CH2Cl  CH3CH2I
acetone
alc.KOH
III. CH3CH2Cl  C
(i) A, B, C  . (1)
(ii) -II   . (1)
(iii) -III , alc. KOH-  aqueous KOH 
   ? (1)

24. (i)   ,
    .
 ? (2)
(ii) HCN   CH3CHO-  
   . (1)

25. (i)      .
 ? (1)
(ii)    4-  
 ? (2)

26.     
 ,   
.

SY-425 9 P.T.O.

Answer any 4 questions from 27 to 31. Each carries 4 scores. (4  4 = 16)
27. (i) Define Van’t Hoff factor. (1)
(ii) A solution is prepared by dissolving 25 mg of K 2SO4 in water to get 2 litre of
solution at 25 C. If the solute completely dissociates in solution, calculate its
osmotic pressure.
(molecular mass of K2SO4 = 174 u; R = 0.0821 L atm K–1 mol–1) (3)

28. (i) The conductivity of an electrolytic solution decreases as dilution increases.
Why ? (1)
(ii) Explain the variation of molar conductivity with dilution in the case of strong
and weak electrolytes. (2)
(iii) State Kohlrausch’s law. (1)

29. Consider the complex species, Hexa-aqua-titanium (III) ion and answer the following :
(i) Identify the geometry of the species. (½)
(ii) Give its structural formula. (½)
(iii) Sketch the energy level diagram representing the crystal field splitting of
d-orbitals of Ti3+ in this species. (2)
(iv) Give reason for the blue green colour of this ion in solution. (1)

30. Given, two haloalkanes A and B :
Br
|
A : CH3 – CH2 – CH2 – Br B : CH3 – CH – CH3

(i) How A and B are prepared from propene ? (2)
(ii) Which among A and B follows SN1 reaction more easily ? Justify the answer. (2)

31. Explain with suitable examples :
(i) Aldol condensation (2)
(ii) Hell – Volhard – Zelinsky reaction. (2)
___________

SY-425 10

27  31    4  .
4  . (4  4 = 16)
27. (i) ‘  ’ . (1)
(ii) 25 mg K2SO4   2   . 25 C
     ,
 ‘ ’ .
(K2SO4-  = 174 u; R = 0.0821 L atm K–1 mol–1) (3)
28. (i)     
  .  ? (1)
(ii)  ,   
   
 . (2)
(iii)   . (1)

29. ‘ (III)  ’   
   :
(i)   . (½)
(ii)   . (½)
(iii) , Ti3+- d-  ‘  ’
      . (2)
(iv)       
 ? (1)

30. A, B      :
Br
|
A : CH3 – CH2 – CH2 – Br B : CH3 – CH – CH3
(i) A, B   ‘’   ? (2)
(ii) A, B   SN1 , 
 ?  . (2)

31.    :
(i)   (2)
(ii)  –  –  . (2)
___________

SY-425 11 P.T.O.

SY-425 12