CBSE Class 12 Question Paper 2026 Solution Air Conditioning & Refrigeration

FOR CBSE CLASS 12 EXAM PREPARATION

CBSE Class 12 2026
Question Paper
Solution · Air
Conditioning,
Refrigeration
EXAM YEAR TYPE

CBSE Class 12 2026 Question Paper Solution
SUBJECT

Air Conditioning, Refrigeration

Notes · Sample Papers · Previous Year Papers · Mock Tests

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Strictly Confidential ag
Marking Scheme

(For Internal and Restricted use only)
Senior Secondary School Examination, 2026 (XIIth)
SUBJECT NAME : Air Conditioning and Refrigeration
(Q.P. CODE 827/315 )

General Instructions: -
1 The CBSE has decided to introduce On Screen Marking (OSM) for the evaluation of
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Class XII answer Book with the 2026 Examination.
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You are aware that evaluation is the most important process in the actual and
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correct assessment of the candidates. A small mistake in evaluation may lead to
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serious problems which may affect the future of the candidates, education system
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and teaching profession. To avoid mistakes, it is requested that before starting
evaluation, you must read and understand the spot evaluation guidelines carefully.
3 “Evaluation policy is a confidential policy as it is related to the confidentiality
of the examinations conducted, evaluation done and several other aspects.
Its leakage to public in any manner could lead to derailment of the
examination system and affect the life and future of millions of candidates.
Sharing this policy/document to anyone, publishing in any magazine and
printing in Newspaper/Website, etc. may invite action under various rules of
the Board and IPC.”
4 Evaluation is to be done as per instructions provided in the Marking Scheme. It
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should not be done according to one’s own interpretation or any other
consideration. Marking Scheme should be strictly adhered to and religiously

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followed. However, while evaluating, answers which are based on latest

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information or knowledge and/or are innovative, they may be assessed for

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their correctness otherwise and due marks be awarded to them. In Class-XII,
while evaluating two competency-based questions, please try to understand
given answer and even if reply is not from marking scheme but correct
competency is enumerated by the candidate, due marks should be awarded.
5 The Marking scheme carries only suggested value points for the answers.
These are in the nature of Guidelines only and do not constitute the complete
answer. The students can have their own expression and if the expression is
correct, the due marks should be awarded accordingly.
6 The Head-Examiner must go through the first five answer books evaluated by each

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evaluator on the first day, to ensure that evaluation has been carried out as per the

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instructions given in the Marking Scheme. If there is any variation, the same should
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be zero after deliberation and discussion. The remaining answer books meant for
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evaluation shall be given only after ensuring that there is no significant variation in m
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Evaluators will mark ( √ ) wherever answer is correct. For wrong answer CROSS ‘X’

ag be marked. Evaluators will not put right (✓) while evaluating which gives an
impression that answer is correct and no marks are awarded. This is most
common mistake which evaluators are committing.
8 If a question has parts, please award marks on the right-hand side for each part in
the OSM Portal. Marks awarded for different parts of the question will be totaled up
by the OSM System.
9 If a question does not have any parts, marks must be awarded in the left-hand
margin in the OSM Portal. This may also be followed strictly.

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10 No marks to be deducted for the cumulative effect of an error. It should be
penalized only once.
11 A full scale of marks __________ (example 0 to 80/70/60/50/40/30 marks as given
in Question Paper) has to be used. Please do not hesitate to award full marks if the
answer deserves it.
12 Every examiner has to necessarily do evaluation work for full working hours i.e., 8
hours every day and evaluate 20 answer books per day in main subjects and 25
answer books per day in other subjects (Details are given in Spot Guidelines).This
is in view of the reduced syllabus and number of questions in question paper.
13 Ensure that you do not make the following common types of errors committed by
the Examiner in the past :-
● Answers marked as correct, but marks not awarded. (Ensure that the right tick
mark is correctly and clearly indicated. It should merely be a line. Same is with
the X for incorrect answer.)
● Half or a part of answer marked correct and the rest as wrong, but no marks
awarded.
14 While evaluating the answer books if the answer is found to be totally incorrect, it
should be marked as cross (X) and awarded zero (0) Marks.
15 The Examiners should acquaint themselves with the guidelines given in the
“Guidelines for Spot Evaluation” before starting the actual evaluation.
16 The candidates are entitled to obtain photocopy of the Answer Book on request on
payment of the prescribed processing fee. All Examiners/Additional Head
Examiners/Head Examiners are once again reminded that they must ensure that
evaluation is carried out strictly as per value points for each answer as given in the
Marking Scheme.
17 If a candidate attempts both alternatives/options in a question where only one
option/ alternative is required to be attempted, the Evaluator shall award
marks in both the options. The system will take the higher of two scores and
disregard the other response.
18 In a question having two options/alternatives, if a candidate has attempted
only one, then the evaluator shall mark “NA” (Not attempted) against the
option that has not been attempted by the candidate.

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MARKING SCHEME
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Air Conditioning and Refrigeration (Subject Code- 827)
(PAPER CODE: 315) (P3150827)
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Q. No. EXPECTED OUTCOMES/VALUE POINTS Unit Marks
SECTION – A
(Objective Type Questions)
1. Answer any 4 out of given 6 questions on employability skills. 4x1=4
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(i)
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Noun, Pronoun, Adjective, Verb, Adverb are the basic parts of (Unit-1, 1
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speech.
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(ii) (B) Self Confidence. (Unit-2, 1

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(iii) (D)a Graphic. (Unit-3, 1
Page No.45)
(iv) (B) Yoga. (Unit-4, 1
Page No.)
(v) (C) Recycle bank. (Unit-5, 1
Page No.117)
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(vi) Motivation is derived from the word ‘motive’. It indicates a (Unit-2, 1

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directing behaviour towards a certain goal. Page No.24)
2.
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Answer any 5 out of the given 7 questions. 5x1=5
(i) Answer : (D)
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Cooling with adiabatic UNIT-1 1
(ii) Answer : (A) Convection UNIT-2 1
(iii) Answer : (A) Condenser UNIT-3 1
(iv) Answer : (A) By shutting off the compressor UNIT-4 1
(v) Answer : (D) Liquidizer UNIT-5 1
(vi) Answer : (A) Waster UNIT-6
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(vii)mAnswer : (B) Forced convection air cooled c. o
UNIT-3 1
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(iii) Answer : (A) air UNIT-5 1
(iv) Answer : (D) Overheating and burn out of motor winding UNIT-4 1
(v) Answer : (A) Finned evaporator UNIT-3 1
(vi) Answer : (B) Humidification UNIT-1 1
(vii) Answer : (B) to maximise temperature fluctuations. UNIT-2 1
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4. Answer any 5 out of the given 6 questions. 5x1=5
(i) Answer : (B) Sensible heating UNIT-1 1
(ii) Answer : (D) PUF UNIT-2 1
(iii) Answer : (B) Trichloro monofluoro methane UNIT-3 1
(iv) Answer : (A) Water cooled condenser UNIT-4 1
(v) Answer : (C) Dipping ice in hot water UNIT-5 1
(vi) Answer : (D) Register UNIT-6 1
5. Answer any 5 out of the given 6 questions. 5x1=5
(i) Answer : (D) Chilling and Freezing UNIT-5 1
(ii) Answer : (B) AHU UNIT-6 1
(iii) Answer : (C) Refrigerant UNIT-4 1
(iv) Answer : (A) R-134a UNIT-3 1
(v) Answer : (D) Conduction UNIT-2 1
(vi) Answer : (B) Ventilation of air UNIT-1 1
6. Answer any 5 out of the given 6 questions. 5x1=5
(i) Answer : (B) halocarbon refrigerants UNIT-3 1
(ii) Answer : (A) Reduced plenum duct system UNIT-2 1
(iii) Answer : (A) Hot wire relay UNIT-4 1
(iv) Answer : (D) −24C to −40C UNIT-5 1

(v) Answer : (D) Ceiling fan UNIT-6 1
(vi) Answer : (D) to absorb moisture from the refrigerant UNIT-3 1
SECTION-B
(Subjective Type Questions)
Answer any 3 out of the given 5 questions on employability skills. 3x2=6
Answer each question in 20-30 words.
7. The four skills are – Listening, Speaking, Reading, Supporting parts Unit-1
of speech :- Writing. Page no.
(i) Articles – the words ‘a’, ‘an’ and ‘the’ are known as articles. 12,13
(ii) Conjunction – These are words that join two nouns, phrases
or sentences
(iii) Prepositions – It connect one word with another to show the
relationship between them.
(iv) Interjection – These words express strong emotions. They
have an exclamation mark at the end.

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se 8. The 4 ways to manage stress :-
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½x4=2
• Keep your thoughts in present. a Page No.26)
• Talk to friends and family for comfort.
• Practice meditation and yoga
• Stay positive and analyse what is going wrong in a certain
situation. Resolving the situation is easy once understood.

9. Text formatting necessary in a spreadsheet are – (Unit-3,
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• They are easy to read and understand. Page No.54) 1+1=2
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Important points are clearly highlighted.
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Two ways to
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(ii) Align (arrange) text in a cell
(iii) Highlight text

10. The 4 government schemes that help small scale entrepreneurs gain (Unit-4, 2
capital – ½x4=2
Page No.92)
(i) Government Mudra Yojana
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(ii) Credit Guarantee Scheme
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(iii) Stand-up India Scheme
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(iv) P.M. employment Generation lPrograms.
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11. These are some plants, which are used to make our home toxin Free (Unit-5, ½x4=2
– Areca palm, Rubber plant, Snake plant, Aloe vera plant, Spider
plant etc. Page No.114)

Answer any 3 out of the given 5 questions in 20-30 words each. 3x2=6

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12. The heating of air, without any change in its specific humidity is UNIT-1 2

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known as sensible heating. In this process, D.B.T of air increases,
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14. To manufacture transparent good quality ice, following steps should UNIT-5 1+1=2
be taken :
1. Water should be given preliminary chemical treatment, and
filtered before filling in cans.
2. To remove the dissolved gases from the freezing water and to
take out solid impurities, air agitation is done in the cans.
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15. The air supplied to the conditioned spaces must be free from all UNIT-6 2
foreign matter such as dirt, fumes, smoke and harmful bacteria. In
order to clean the contaminated air we use filters.

16. The function of a condenser is to remove heat of the hot vapour UNIT-3 2
refrigerant discharged from the compressor. This heat is removed
through the walls of the condenser tubes to the cooling medium.

Answer any 2 out of the given 3 questions in 30-50 words each. 2x3=6

17. Conduction : UNIT-2 1+1+1=3
Heat is transferred between objects or within an object through
direct contact. The particles in the hotter region vibrate more
vigorously, and this energy is passed on to neighbouring particles,
leading to a transfer of heat from the hotter to the cooler region.
Conduction is most effective in solids.
Convection :
Heat is transferred through the movement of fluids (liquid and
gases). When a fluid is heated, It expands, becomes less dense, and
rises. Cooler, dense fluid then moves in to replace it, creating a
continuous cycle of movement and heat transfer.
Radiation :
In radiation, heat is transferred in the form of electromagnetic
waves. For radiative heat transfer, therefore, the presence of a
medium is not necessary.

18. When two quantities of air having different enthalpies and different UNIT-1 3
specific humidities are mixed, the final condition of the air mixture
depends upon the masses involved, on the enthalpy and specific
humidities of each of the constituent masses which enter the
mixture.
The adiabatic mixing process is represented on the psychrometric
chart by a point which lies on the straight line joining the points of
two constituents masses. The final condition of the mixture lies on
this straight line and this point divides the line in the inverse ratio of
mixture masses.

19. 1. The refrigerant is stable and is non-toxic, non-corrosive and UNIT-3 ½x6=3
non-flammable
2. The boiling point of R-22 is −41C at atmospheric pressure
3. It has a latent heat of 216.5 kJ/kg at −15C
4. The refrigerant has good solubility in oil.
5. It is used with reciprocating and centrifugal compressors
6. The cylinder colour code for R-22 is green.
etc.

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Answer any 3 out of the given 5 questions in 50-80 words each. 3x4=12

20. A well labelled appropriate diagram. UNIT-2 2+2=4

In this system, conditioned air is introduced through the
openings located in the ceiling and removed through the openings
made in floor or in walls near the floor. The downward system
should endeavour to spread the incoming air uniformly above the
occupied space.
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21. The capillary tube is the simplest of the refrigerant flow controls, UNIT-3 2+2=4

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consisting merely of a fixed length of small diameter tubing
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installed between the condenser and the evaporator. Because of the
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high frictional resistance resulting from its length and small bore
(diameter) and because of the throttling effect resulting from the
gradual formation of flash gas in the tube as the pressure of the
liquid is reduced below its saturation pressure the capillary tube acts
to restrict or meter the flow of liquid from the condenser to
evaporator and also to maintain the required operating pressure
differential between those two units.

Advantages of capillary tube :
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It is simple in construction and no maintenance is required.
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2. System using this device doesn't require receiver.

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Disadvantages of capillary tube :

1. The refrigerant must be free from moisture and dirt otherwise
it will choke the tube and stop the flow of refrigerant.

2. It cannot be used with high fluctuating load conditions.

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etc.
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. A well labelled appropriate diagram. s emUNIT-4
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This control is used as a safety control. The compressor
stopped by cutting off the power supply given to the motor of
compressor whenever the discharge pressure of the compressor
becomes excessive. This is necessary to prevent the possible
damages of the equipments. When the pressure returns to the
normal, the control acts to close the power supply and starts the
compressor.

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23. A well labelled appropriate diagram. UNIT-5 4

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24. In a central station air conditioning system, all the components of UNIT-6 4
the system are grouped together in one central room and
conditioned air is distributed from the central room to the required
places through extensive duct work. It is generally used for the load
above 25TR and 2500 cubic meter/min. of conditioned air. The
central plants require the following components and all the
components are assembled on the site :
1. cooling and dehumidifying coils
2. heating coils
3. blower with motor
4. sprays for cooling, dehumidifying or washing.
5. air cleaning equipments
6. a control device.
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