CBSE Class 12 Question Paper 2024 Air Conditioning and Refrigeration

CBSE

Series &RQPS SET-4

Q.P. Code 351
 -   - 
Roll No. -    
Candidates must write the Q.P. Code
on the title page of the answer-book.

=       -    15  
=       -  24   
= -        -    -  -   
=

=  -     15        -     10.15 
   10.15   10.30     -        
-      
= Please check that this question paper contains 15 printed pages.
= Please check that this question paper contains 24 questions.
= Q.P. Code given on the right hand side of the question paper should be written
on the title page of the answer-book by the candidate.
= Please write down the serial number of the question in the answer-book
before attempting it.
= 15 minute time has been allotted to read this question paper. The question
paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the
candidates will read the question paper only and will not write any answer on
the answer-book during this period.

AIR-CONDITIONING AND REFRIGERATION

{ZYm©[aV g‘¶ : 3 KÊQo A{YH V‘ A§H : 60
Time allowed : 3 hours Maximum Marks : 60

3512 271 Page 1 P.T.O.

(i)       
(ii)  -  , -  -  24   
(iii) -        -       
(iv)   (6 + 18 =) 24   ,   3    ()  
(6 + 11 =) 17      
(v)              
(vi) : (30 ):
(1)    06   
(2)      
(3)       
(4)  /          
(vii) : (30 ):
(1)    18   
(2)   11    
(3)       
(4)  /          

–

1. 6 4 (4 1 = 4)
(i)        ? 1
(ii)    ? 1
(iii)         1
(iv)      1
(v)    ? 1
(vi)  “”     ()  ? 1
3512 Page 2

General Instructions :
(i) Please read the instructions carefully.
(ii) This Question Paper consists of 24 questions in two sections : Section-A
& Section-B.
(iii) Section-A has Objective Type Questions whereas Section-B contains
Subjective Type Questions.
(iv) Out of the given (6 + 18 =) 24 questions, a candidate has to answer
(6 + 11 =) 17 questions in the allotted (maximum) time of 3 hours.
(v) All questions of a particular section must be attempted in the correct
order.
(vi) Section-A : Objective Type Questions (30 Marks) :
(1) This Section has 06 questions.
(2) There is no negative marking.
(3) Do as per the instructions given.
(4) Marks allotted are mentioned against each question/part.
(vii) Section-B : Subjective Type Questions (30 Marks) :
(1) This Section has 18 questions.
(2) A candidate has to do 11 questions.
(3) Do as per the instructions given.
(4) Marks allotted are mentioned against each question/part.

SECTION – A
(Objective Type Questions)

1. Answer any 4 questions out of the given 6 questions on
Employability Skills : (4 1 = 4)
(i) What is a row in a spreadsheet ? 1
(ii) What is decisiveness ? 1
(iii) Write the name of any two green house gases. 1
(iv) Write one exclamatory sentence. 1
(v) What is stress ? 1
(vi) Is “text” a type of data ? 1

3512 Page 3 P.T.O.

2. 7 5 : (5 1 = 5)
(i)           1
(A)   (B) 
(C)   (D)  
(ii)                ? 1
(A)   D.P.T. 
(B)   W.B.T. 
(C)   D.B.T.  W.B.T.      
(D)   D.B.T. 
(iii)                 ? 1
(A)   (B) 
(C)  (D)  
(iv)          1
(A)  
(B)  
(C)    
(D)           
(v) ..   ________      1
(A)    (B)   
(C) (A)  (B)  (D)   
(vi)       _______      1
(A) 0.75   1.5  (B) 1.5   2.5 
(C) 5.0   50  (D) 100   
(vii)            0°     
  ? 1
(A)  (B) 
(C)  (D) 

3. 7 6 (6 1 = 6)
(i)           ? 1
(A) NH3 (B) H2O
(C) CHClF2 (D) CCl2F2

3512 Page 4

2. Answer any 5 out of the given 7 questions : (5 1 = 5)
(i) Glycols are also known as : 1
(A) Primary refrigerants (B) Brines
(C) Freezing solutions (D) Antifreeze solutions
(ii) A sling psychrometer is used to measure which one of the following ? 1
(A) D.P.T. of air
(B) W.B.T. of air
(C) D.B.T. and W.B.T. of air simultaneously
(D) D.B.T. of air
(iii) Pure water is filled in which one of the following components for
making the ice ? 1
(A) Brine tank (B) Condenser
(C) Evaporator (D) Ice can
(iv) The thermal conductivity of an insulating material should be : 1
(A) extremely high
(B) extremely low
(C) moderately high
(D) Thermal conductivity has no roll in insulating materials.
(v) H.P. cutout is essential in _______ refrigeration systems. 1
(A) Air cooled condenser
(B) Water cooled condenser
(C) Both (A) and (B)
(D) Natural convection condensers
(vi) Capacity of a packaged air conditioning system lies between : _______ 1
(A) 0.75 TR to 1.5 TR (B) 1.5 TR to 2.5 TR
(C) 5.0 TR to 50 TR (D) More than 100 TR
(vii) Which one among the following is a secondary refrigerant when it is
used above 0 °C ? 1
(A) Ammonia (B) Water
(C) Air (D) Brine

3. Answer any 6 out of the given 7 questions : (6 1 = 6)
(i) Which one among the following is not a primary refrigerant ? 1
(A) NH3 (B) H2O
(C) CHClF2 (D) CCl2F2

3512 Page 5 P.T.O.

(ii)         DBT  1
(A)           
(B)           
(C)    
(D)    
(iii)            ? 1
(A)  (B) 
(C)  (D)  
(iv)               1
(A)      (B)     
(C)      (D)     
(v)        -   1
(A)  (B)  
(C)   (D) 
(vi)             ? 1
(A)  
(B) - 
(C)    -  
(D)  ..
(vii)                ? 1
(A)    (B)  
(C)    (D) 

4. 6 5 : (5 1 = 5)
(i)                
  ? 1
(A)  (B) 
(C)  (D) 

3512 Page 6

(ii) In the sensible heating process of air the DBT of air is 1
(A) increased without affecting moisture content of air.
(B) increased with increase in moisture content of air.
(C) increased
(D) decreased
(iii) Freezing tanks are used in which one of the following ? 1
(A) Air conditioners (B) Water coolers
(C) Refrigerators (D) Ice plants
(iv) For a good air distribution system, the flow of air should be
preferably : 1
(A) towards the head of the occupants.
(B) towards the feet of the occupants.
(C) towards the back of the occupants.
(D) towards the faces of the occupants.
(v) The air conditioning used for winter is : 1
(A) Refrigerator (B) Heat pump
(C) Heat engine (D) Heater
(vi) In a voltage relay which one among the following is used ? 1
(A) Electromagnetic coil
(B) Bi-metal strip
(C) Electromagnetic coil and bi-metal strip both
(D) An I.C.
(vii) Which one among the following devices is used as an expansion
device in a window air conditioner ? 1
(A) Automatic expansion valve (B) Float valve
(C) Thermostatic expansion valve (D) Capillary

4. Answer any 5 out of the given 6 questions : (5 1 = 5)
(i) Which one among the following components is used to remove the
latent heat of refrigerant ? 1
(A) Compressor (B) Evaporator
(C) Condenser (D) Capillary

3512 Page 7 P.T.O.

(ii)                ? 1
(A)          
(B)         
(C)          DBT   
(D)           DBT     
(iii)                
    ? 1
(A)  (B) 
(C)  (D) 
(iv)               
      ? 1
(A)  (B)  
(C)  (D) 
(v)           ? 1
(A)    (B)   
(C)    (D)      
(vi)               
  ? 1
(A)   (B)  
(C)     (D)    

5. 6 5 : (5 1 = 5)
(i)          ? 1
(A)   (B)  
(C)  (D)  
(ii)              
        ? 1
(A)   (B)  
(C)    (D)  

3512 Page 8

(ii) Humidification of air is performed to achieve which one of the
following ? 1
(A) Decrease the moisture content of air.
(B) Increase the moisture content of air.
(C) Increase the DBT of air with increase in moisture content of air.
(D) Decrease the DBT of air with decrease in moisture content of
air.
(iii) Which one among the following components is used to convert liquid
refrigerant into vapour refrigerant ? 1
(A) Compressor (B) Evaporator
(C) Condenser (D) Capillary
(iv) To supply the conditioned air from conditioning plant to the occupied
space which one among the following is used ? 1
(A) Canals (B) Open spaces
(C) Fans (D) Ducts
(v) Which one among the following is not an electromagnetic relay ? 1
(A) Current starting relay
(B) Voltage starting relay
(C) Hot wire relay
(D) Current and voltage starting relay both
(vi) Which one among the following points are not to be considered in
designing of a cold storage ? 1
(A) Storage temperature (B) Relative humidity
(C) Air motion (D) Number of occupants

5. Answer any 5 out of the given 6 questions : (5 1 = 5)
(i) Which one among the following is a safety control ? 1
(A) Solenoid Valve (B) Overload protector
(C) Capacitor (D) Float valve
(ii) Which one among the following filters are extensively used in
industrial areas to absorb harmful soluble gases ? 1
(A) Wet filters (B) Dry filters
(C) Centrifugal dust collector (D) Electric filter

3512 Page 9 P.T.O.

(iii)         1
(A)         
(B)         
(C)      
(D)       
(iv)               ? 1
(A)  (B) 
(C)  (D) 
(v)              ? 1
(A)    (B)   
(C)   (D)  
(vi)         _________       1
(A) – 40 °C  – 80 °C (B) – 24 °C  – 40°C
(C) 0 °C  – 40 °C (D) 0 °C  – 24 °C

6. 6 5 : (5 1 = 5)
(i)          : 1
(A)    (B)  
(C)   (D)      
(ii)          ? 1
(A)    (B)   
(C)    (D)   
(iii)                
   ? 1
(A)       
(B)          
(C)         
(D)          

3512 Page 10

(iii) The function of an expansion device in a refrigeration system is to 1
(A) convert vapour refrigerant into liquid refrigerant.
(B) convert liquid refrigerant into vapour refrigerant.
(C) increase the pressure of liquid refrigerant.
(D) reduce the pressure of liquid refrigerant.
(iv) The heat transfer in solids takes place by which one of the following
modes of heat transfer ? 1
(A) Evaporation (B) Conduction
(C) Convection (D) Radiation
(v) Which one among the following fans is employed with duct systems ? 1
(A) Ceiling fan (B) Axial flow fan
(C) Centrifugal fan (D) Propeller fan
(vi) In air blast freezers, the air temperature ranging from ______ 1
(A) – 40 °C to – 80 °C (B) – 24 °C to – 40°C
(C) 0 °C to – 40 °C (D) 0 °C to – 24 °C

6. Answer any 5 out of the given 6 questions : (5 1 = 5)
(i) An overload protector protects the compressor motor by : 1
(A) Excessive current
(B) Overheating
(C) Overcooling
(D) Excessive current and overheating both
(ii) Which one among the following is a psychrometric process ? 1
(A) Humidification of air (B) Distribution of air
(C) Cleaning of air (D) Ventilation of air
(iii) Fins are used on heat transfer surfaces due to one among the
following reasons : 1
(A) To make the surface clean
(B) To decrease the rate of heat transfer
(C) To increase the rate of heat transfer
(D) To maintain the constant rate of heat transfer

3512 Page 11 P.T.O.

(iv)                 ? 1

(A)     (B)    
(C)  (D) 
(v) F.C.U.             ? 1

(A)    (B) DX 

(C)    DX    (D)   
(vi)              ? 1

(A)  (B) 
(C)  (D) 

–

5 3 20-30

(3 2 = 6)
7.     ? 2

8.          ? 2

9.          ? 2

10.     ?     2

11.           2

3512 Page 12

(iv) In a domestic refrigerator which one among the following types of
condensers is used ? 1
(A) Natural convection air cooled
(B) Forced convection air cooled
(C) Water cooled
(D) Evaporative
(v) F.C.U. is used in which one among the following air conditioning
systems ? 1
(A) All water system
(B) DX system
(C) All water and DX system both
(D) All air system
(vi) Which one among the following is not an essential component of a
cold storage ? 1
(A) Compressor (B) Condenser
(C) Capillary (D) Evaporator

SECTION – B
(Subjective Type Questions)
Answer any 3 out of the given 5 questions on Employability Skills
in 20-30 words each : (3 2 = 6)
7. Who are the professional entrepreneurs ? 2

8. What is the need to format cells and contents ? 2

9. How can we promote the waste exchange ? 2

10. What is a sentence ? Write an example. 2

11. Write any two ways to maintain positive attitude. 2

3512 Page 13 P.T.O.

5 3 20-30 : (3 2 = 6)
12.              2

13.    - ()     2

14.              2

15.               2

16.    ?    2

3 2 30-50 : (2 3 = 6)
17.              3

18.      ?             
  3

19.           3

5 3 50-80 : (3 4 = 12)
20.        4

21.                4

22.              4

23.      ?       4

24.              4
____________

3512 Page 14

Answer any 3 out of the given 5 questions in 20-30 words each : (3 2 = 6)
12. Write the name of the refrigeration system employed in an ice plant and
cold storage. 2

13. Explain air-water (combined) system used in air-conditioning. 2

14. Explain the function of an air cooled condenser in a refrigeration system. 2

15. Write the name of psychrometric process which is performed by a
domestic air cooler. 2

16. What is convection ? Explain. 2

Answer any 2 out of the given 3 questions in 30-50 words each :
(2 3 = 6)
17. Explain plate surface evaporator with a neat sketch. 3

18. What is a thermal insulating material ? Write the functions of insulating
materials used for a refrigerated space. 3

19. Explain De-humidification process with the help of psychrometric chart. 3

Answer any 3 out of the given 5 questions in 50-80 words each :
(3 4 = 12)
20. Explain the principle of evaporation cooling. 4

21. Explain ejector system of air-distribution with a neat sketch. 4

22. Explain automatic expansion valve with a neat sketch. 4

23. What is an air conditioning system ? Give classification of air conditioning
systems. 4

24. Explain low pressure cutout with a neat sketch. 4

____________

3512 Page 15 P.T.O.

3512 271 Page 16

CBSE STUDY MATERIAL

CBSE Board

INFORMATION CLASS STUDY MATERIAL

1 Time Table 09 Sample Paper
10 Sample Paper
2 Result
11 Sample Paper
3 Syllabus 12 Sample Paper

OTHER RESOURCES
09 Question Paper
Maps of India, Maps of World
Writing Skill Formats 10 Question Paper
Periodic Table 11 Question Paper
12 Question Paper
Class 9 Notes
Class 10 Notes
NCERT Book
Class 11 Notes
Class 12 Notes NCERT Solutions

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