Kerala Plus One Question Paper 2025 Chemistry

KERALA BOARD

QUESTION
PAPER
2025
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Kerala Board of Public
Examinations

FY-325
Reg. No. : ......................................

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

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

FY-325 1 P.T.O.

Answer any 4 questions from 1 to 5. Each carries 1 score. (4  1 = 4)
1. Identify the limiting reagent in the reaction 2A + 4B  3C + 4D, when 5 moles of A
react with 6 moles of B.

2. Which of the following elements will gain one electron more readily ?
(a) S (g) (b) Na (g)
(c) O (g) (d) Cl (g)

3. Analyse the following statements and choose the correct option :
Statement I : Sodium chloride formed by the action of chlorine gas on sodium
metal is a stable compound.
Statement II : This is because sodium and chloride ions acquire octet in sodium
chloride formation.
(a) Both statement I and statement II are true and statement II is the correct
explanation of statement I.
(b) Both statement I and statement II are true but statement II is not the correct
explanation of statement I.
(c) Statement I is true but statement II is false.
(d) Both statement I and statement II are false.

4. The conjugate base of H2O is _____ .

5. How many  bonds are present in the following molecule ?
HCCCH=CHCH3

Answer any 8 questions from 6 to 15. Each carries 2 scores. (8  2 = 16)

6. Define the law of multiple proportions. Explain it with one example.

FY-325 2

1  5    4  .
1  . (4  1 = 4)
1.    A  5  B  6
    .
2A + 4B  3C + 4D

2.      
  ?
(a) S (g) (b) Na (g)
(c) O (g) (d) Cl (g)

3.      
.
 I :    
     
 .
 II : ,    
  .
(a)  I ,  II  ,  II 
 I   .
(b)  I   II     II
  I   .
(c)  I ,   II .
(d)  I   II  .

4. H2O     _________.

5.        ?
HCCCH=CHCH3

6  15    8  .
2  . (8  2 = 16)
6.   .   
.

FY-325 3 P.T.O.

7. Define wavelength and find out the wavelength of electromagnetic wave shown
below :

8. Draw the boundary surface diagram of s and p orbitals.

9. Match the following :
Column – I Column – II
(i) CH4 (a) sp3d
(ii) PCl5 (b) sp3d2
(iii) BeF2 (c) sp3
(iv) SF6 (d) sp2
(e) sp

10. Identify the state functions and path functions out of the following :
enthalpy, heat, work, free energy.

11. What are buffer solutions? Give an example.

12. Arrange the following compounds in the increasing order of oxidation number of
chlorine :
NaClO, KClO2, Cl2, ClO2

13. Write the IUPAC names of the following compounds and identify the type of
isomerism shown by them :
(i) CH3COCH3

(ii) CH3CH2CHO

FY-325 4

7.     
   

8. s, p     .

9.   :
 – I  – II
(i) CH4 (a) sp3d
(ii) PCl5 (b) sp3d2
(iii) BeF2 (c) sp3
(iv) SF6 (d) sp2
(e) sp

10.       
.
, , ,  

11.    ?   .

12.      
  .
NaClO, KClO2, Cl2, ClO2

13.    IUPAC   
   .
(i) CH3COCH3
(ii) CH3CH2CHO

FY-325 5 P.T.O.

14. What are the products obtained when propene undergoes ozonolysis ?

15. Complete the following reactions:

Ni
(i) + 3H2 


Anhyd. AlCl3
(ii) + Cl2 

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

16. (i) What is the mass percent of carbon in carbon dioxide ? (1)
(ii) Which of the following solutions have the same concentration ? (2)
(a) 20 g of NaOH in 200 ml of solution
(b) 0.5 mol of KCl in 200 ml of solution
(c) 40 g of NaOH in 100 ml of solution
(d) 20 g of KOH in 200 ml of solution

17. (i) An atomic orbital has n = 2. What are the possible values of l and m1 ? (2)
(ii) Which of the following orbitals are possible ? (1)
2s, 2p, 2d and 3f

18. Analyse the graph given below and answer the following questions :

(i) Identify the elements showing deviation in ionisation enthalpy from the general
trend. (1)
(ii) Explain the reason for deviation in each case. (2)

FY-325 6

14.     
 ?
15.    .
Ni
(i) + 3H2 


Anhyd. AlCl3
(ii) + Cl2 

16  26    8 
. 3  . (8  3 = 24)
16. (i)       ? (1)
(ii)     
  ? (2)
(a) 200 ml  20 g NaOH
(b) 200 ml  0.5  KCl
(c) 100 ml  40 g NaOH
(d) 200 ml  20 g KOH
17. (i)    n = 2 . l, m1  
  ? (2)
(ii)      ? (1)
2s, 2p, 2d, 3f
18.        
 .

(i)     
   . (1)
(ii)   . (2)
FY-325 7 P.T.O.

19. (i) Define covalent radius. (1)

(ii) Explain why cations are smaller and anions larger in radii than their parent
atoms ? (2)

20. (i) Discuss the significance of dipole moment. (1)

(ii) Represent diagrammatically the bond moments and the resultant dipole moment
in CO2 and NF3. (2)

21. At 298 K, Kp for the reaction N2O4(g) 2NO2(g) is 0.98. Calculate the change in
standard free energy and predict whether the reaction is spontaneous or not.

22. (i) On the basis of Le Chatelier principle explain how temperature and pressure can
be adjusted to increase the yield of ammonia in the following reaction :

N2(g) + 3H2(g) 2NH3(g), H = – 92.38 kJ mol–1 (2)

(ii) What will be the effect of addition of argon to the above reaction mixture at
constant volume ? (1)

23. Balance the following ionic equation :

Cr2O72– + Fe2+ + H+  Cr3+ + Fe3+ + H2O

24. (i) Explain the terms Inductive and Electromeric effects. (2)

(ii) Which electron displacement effect explains the following correct orders of
acidity of the carboxylic acids ?

Cl3CCOOH > Cl2CHCOOH > ClCH2COOH (1)

25. Draw Newman projections for the eclipsed and staggered conformations of ethane.
Which of these conformations is more stable ?

FY-325 8

19. (i)    . (1)
(ii)      
    ? (2)

20. (i)     . (1)
(ii) CO2, NF3    
     
. (2)

21. 298 K-,    Kp
N2O4(g) 2NO2(g) 0.98 .   
 ,     
.

22. (i)     
     
   .
N2(g) + 3H2(g) 2NH3(g), H = –92.38 kJ mol–1 (2)
(ii)      
    ? (1)

23.     .
Cr2O72– + Fe2+ + H+  Cr3+ + Fe3+ + H2O

24. (i) ,    . (2)
(ii)     
       ?
Cl3CCOOH > Cl2CHCOOH > ClCH2COOH (1)

25.  ,    
.     ?
FY-325 9 P.T.O.

26. Identify the products formed in the following reactions :
CCl4
(i) CH2 = CH2 + Br – Br  (1)

(ii) CH3 – CH = CH2 + H – Br  (2)

Answer any 4 questions from 27 to 31. Each carries 4 scores. (4  4 = 16)

27. (i) Write the statement and significance of Heisenberg's uncertainty principle. (2)
(ii) An electron in an atom can be located within a distance of 0.1 Å. What is the
uncertainty involved in the measurement of its velocity ? (mass of electron =
9.1  10–31 kg) (2)

28. Write the molecular orbital configurations N2, Ne2 and show that N2 has a triple bond

in between nitrogen atoms while Ne2 does not exist.

29. (i) State Hess's Law of Constant Heat Summation. (1)
(ii) Construct an enthalpy diagram (Born-Haber cycle) to calculate the lattice
enthalpy of Na+Cl –(s). (3)

30. (i) What is meant by heterogeneous equilibrium? Give an example. (2)
(ii) The value of Kc for the reaction 2A B + C is 2  10–3. At a given time, the

composition of the reaction mixture is [A] = [B] = [C] = 3  10–4 M. Calculate
reaction quotient(Qc) and predict in which direction will the reaction proceed ? (2)

31. Explain the detection of N, S, Cl and Br using sodium fusion extract.
_____________

FY-325 10

26.      :
CCl4
(i) CH2 = CH2 + Br – Br  (1)

(ii) CH3 – CH = CH2 + H – Br  (2)

27  31    4 
. 4  . (4  4 = 16)
27. (i)    
 . (2)
(ii)      0.1 Å 
    
  ? (  = 9.1  10–31 kg) (2)

28. N2, Ne2      
  N2     Ne2
  .

29. (i)    . (1)

(ii) Na+Cl –(s)      
 (- ) . (3)

30. (i)    ?   . (2)

(ii) 2A B + C;   Kc   2  10–3 .
  ,    [A] = [B] =
[C] = 3  10–4 M . Qc     
 ? (2)

31.     N, S, Cl, Br  
.
______________

FY-325 11 P.T.O.

FY-325 12