CBSE Class 12 Solved Papers (2021-2026) – Year-wise Deep Dive

वर्ष 2021: स्पेशल असेसमेंट और मुख्य प्रश्न

(2021 में पैटर्न थोड़ा अलग था, इसलिए इसमें कॉन्सेप्ट पर ज्यादा जोर दिया गया था)
Physics:
Q: Define Electric Dipole Moment. Is it a scalar or vector quantity?
Ans: It is the product of the magnitude of one of the charges and the distance between them. It is a Vector quantity.
हिंदी में: यह दो आवेशों के बीच की दूरी और एक आवेश के परिमाण का गुणनफल है। यह एक सदिश राशि है।

Biology:

Q: Explain ‘Pleiotropy’ with an example.
Ans: When a single gene controls multiple phenotypic traits, it is called Pleiotropy. Example: Phenylketonuria (PKU).
हिंदी में: जब एक ही जीन कई लक्षणों को नियंत्रित करता है, तो उसे प्लीओट्रॉपी कहते हैं।
वर्ष 2022: टर्म-वाइज परीक्षा के महत्वपूर्ण सवाल

Chemistry:

Q: What are ‘Azo Dyes’?
Ans: These are organic compounds containing the -N=N- group, used as coloring agents in textiles.

Business Studies:

Q: Difference between Marketing and Selling.
Ans: Marketing starts before production and focuses on customer satisfaction. Selling starts after production and focuses on converting products into cash.
हिंदी में: मार्केटिंग का उद्देश्य ग्राहक की संतुष्टि है, जबकि सेलिंग का उद्देश्य सिर्फ माल बेचना और पैसा कमाना है।
वर्ष 2023: फुल सिलेबस का कमबैक

Maths:

Q: Find the area of the region bounded by the curve y^2 = x and the lines x=1, x=4.
Ans: इसे \int_{1}^{4} \sqrt{x} dx का उपयोग करके हल करेंगे। इसका उत्तर 14/3 वर्ग इकाई आएगा।

Economics:

Q: What is ‘Repo Rate’?
Ans: It is the rate at which the Central Bank (RBI) lends money to commercial banks for short periods.
हिंदी में: जिस दर पर रिजर्व बैंक (RBI) दूसरे बैंकों को कर्जा देता है, उसे रेपो रेट कहते हैं।

वर्ष 2024: लेटेस्ट पैटर्न और एप्लीकेशन आधारित प्रश्न
Physics:

Q: Why is the core of a transformer laminated?
Ans: To minimize energy loss due to Eddy Currents.
हिंदी में: ट्रांसफार्मर के कोर को परतदार (Laminated) बनाया जाता है ताकि ‘भँवर धाराओं’ (Eddy Currents) के कारण होने वाले ऊर्जा के नुकसान को कम किया जा सके।

Geography:

Q: Explain ‘Sustainable Development’.
Ans: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

वर्ष 2025: हालिया बोर्ड परीक्षा का विश्लेषण
Chemistry:

Q: What is the ‘Fuel Cell’? Give one example.
Ans: Galvanic cells that are designed to convert the energy of combustion of fuels like H_2, CH_4 directly into electrical energy. Example: H_2-O_2 Fuel Cell.

Political Science:

Q: What is the ‘NITI Aayog’?
Ans: It replaced the Planning Commission. It serves as the ‘Think Tank’ of the Government of India.

वर्ष 2026: मॉडल प्रश्न और संभावित पेपर (Bexyhub Special)
English Core:
Drafting a Poster: Create a poster on “Say No to Plastics”.
Tip: Use catchy slogans like “Plastics die hard” and keep the design simple but effective.

Biology:

Q: What is ‘Gene Therapy’?
Ans: A technique that involves replacing a defective gene with a healthy one to treat a genetic disorder.
हिंदी में: खराब जीन को हटाकर स्वस्थ जीन डालना ‘जीन थेरेपी’ कहलाता है।

यह सीबीएसई 12वीं सॉल्व्ड सीरीज (2021-2026) दीपक कुमार द्वारा विशेष रूप से तैयार की गई है। इसमें एनसीईआरटी (NCERT) के लेटेस्ट सिलेबस और बोर्ड मार्किंग स्कीम का पूरा ध्यान रखा गया है। © Bexyhub.in

वर्ष 2021: कोरोना काल के महत्वपूर्ण सवाल
Accountancy:
Q: What is ‘Goodwill’? Why is it called an Intangible Asset?
Ans: Goodwill is the reputation of a firm which helps it earn higher profits. It is intangible because it has no physical existence (we can’t touch it), but it has a real value.
हिंदी में: गुडविल (ख्याति) फर्म की इज्जत है। यह एक अमूर्त संपत्ति है क्योंकि इसे देखा नहीं जा सकता, लेकिन इसकी कीमत होती है।

Maths:

Q: What is a Unit Vector?
Ans: A vector whose magnitude is 1. \hat{a} = \vec{a} / |\vec{a}|.

वर्ष 2022: टर्म-2 स्पेशल
History:
Q: Explain the ‘Mansabdari System’ of Akbar.
Ans: It was a grading system used by the Mughals to fix rank, salary, and military responsibilities.
हिंदी में: यह अकबर द्वारा शुरू की गई एक श्रेणी प्रणाली थी जिससे अधिकारियों का पद और वेतन तय होता था।

Geography:

Q: Difference between Push and Pull factors of Migration.
Ans: Push Factors make a place look less attractive (unemployment, war). Pull Factors make a place look more attractive (better jobs, education).

वर्ष 2023: फुल सिलेबस धमाका
Chemistry:
Q: What is the ‘Reimer-Tiemann Reaction’?
Ans: Treating Phenol with Chloroform in the presence of NaOH results in Salicylaldehyde. (यह रिएक्शन हर साल आती है, इसे ज़रूर रटें)।

Maths (Calculus):

Q: Find the derivative of e^{sin x}.
Ans: Using Chain Rule: d/dx (e^{sin x}) = e^{sin x} \cdot cos x.

वर्ष 2024: लेटेस्ट बोर्ड पैटर्न
Economics:
Q: What is ‘Deficit Financing’?
Ans: When the government spends more than its income and borrows money to cover the gap.
हिंदी में: जब सरकार की कमाई कम और खर्चा ज्यादा हो, तो उस घाटे को पूरा करने के लिए जो व्यवस्था की जाती है, उसे घाटे की वित्त व्यवस्था कहते हैं।

Physics:

Q: Why do stars twinkle but planets don’t?
Ans: Stars are point sources far away, so atmospheric refraction causes their light to flicker. Planets are closer and act as extended sources, so the flickering effect cancels out.

वर्ष 2025: हालिया परीक्षा विश्लेषण
Biology:
Q: What is ‘PCR’ (Polymerase Chain Reaction)?
Ans: It is a technique used to make multiple copies of a specific DNA segment. It involves 3 steps: Denaturation, Annealing, and Extension.

English:

Q: What is the theme of the poem ‘Keeping Quiet’?
Ans: The poet Pablo Neruda emphasizes the need for self-introspection and creating a feeling of mutual understanding among human beings.

वर्ष 2026: Bexyhub प्रेडिक्शन (संभावित प्रश्न)
Accountancy:
Q: What is ‘Cash Flow Statement’ as per AS-3?
Ans: A statement showing inflows and outflows of cash from Operating, Investing, and Financing activities.

Geography:

Q: Why is ‘Digital Divide’ a concern?
Ans: It is the gap between those who have access to modern ICT and those who don’t. It creates inequality in education and jobs.

यह विस्तृत सीबीएसई 12वीं समाधान सीरीज (2021-2026) दीपक कुमार (नर्सिंग ऑफिसर) द्वारा तैयार की गई है। यह पूरी तरह ओरिजिनल और छात्रों के लिए आसान भाषा में है। © Bexyhub.in

गणित (Mathematics) – महत्वपूर्ण सवाल
प्रश्न (Calculus): फलन f(x) = sin x + cos x का अधिकतम मान (Maximum Value) ज्ञात कीजिए।
हल: 1. सबसे पहले f'(x) निकालें: cos x – sin x = 0।

इससे tan x = 1 मिलता है, यानी x = \pi/4।

f”(x) = -sin x – cos x। यहाँ x = \pi/4 रखने पर मान ऋणात्मक आता है।

प्रश्न: ‘प्रतिलेखन’ (Transcription) की प्रक्रिया को समझाइए।
उत्तर: डीएनए (DNA) से आरएनए (RNA) बनने की प्रक्रिया को प्रतिलेखन कहते हैं। यह केंद्रक (Nucleus) के अंदर होती है। इसमें आरएनए पॉलीमरेज एंजाइम मुख्य भूमिका निभाता है।
प्रश्न: मादा जनन तंत्र का आरेख बनाइए।
उत्तर: इसमें अंडाशय (Ovary), अंडवाहिनी (Fallopian Tube), और गर्भाशय (Uterus) शामिल होते हैं।

Physics: Optics & Electrostatics (विस्तृत हल)

Q1: Derive the Mirror Formula for a Concave Mirror and explain its sign convention.
Detailed Answer: Mirror formula 1/f = 1/v + 1/u relates focal length, image distance, and object distance. To derive this, we consider a concave mirror and an object placed beyond its center of curvature. By using similar triangles formed by the rays, we establish the ratio of heights and distances.
Sign Convention (New Cartesian):
All distances are measured from the Pole.
Distances in the direction of incident light are positive (+).
Distances against the direction of incident light are negative (-).
Heights above the principal axis are positive, and below are negative.

Q2: Describe the construction and working of a Van de Graaff Generator.

Construction: It consists of a large hollow metallic sphere supported on insulating pillars. A belt of insulating material (like silk) runs over two pulleys.
Working: It works on the principle of ‘Action of Sharp Points’ and the fact that charge given to a hollow conductor resides on its outer surface. The spray comb gives a positive charge to the belt, which carries it to the sphere. Over time, the potential of the sphere rises to millions of volts.

Biology: Genetics & Human Welfare (दीर्घ उत्तरीय प्रश्न)
Q3: Explain the process of ‘Protein Synthesis’ (Translation) in detail.
Detailed Answer: Translation is the process where the genetic code in mRNA is read to synthesize a specific protein. It occurs in three main stages:
Initiation: The smaller subunit of the ribosome binds to the mRNA at the start codon (AUG). The initiator tRNA carries Methionine.

Elongation: Amino acids are added one by one. The ribosome moves along the mRNA, and peptide bonds are formed between amino acids.

Termination: When the ribosome reaches a stop codon (UAA, UAG, or UGA), the process stops, and the newly formed polypeptide chain is released.

Q4: What is Sewage Treatment? Describe the Primary and Secondary treatment stages.

Primary Treatment: It is a physical process involving filtration and sedimentation to remove large and small particles (grit, floating debris).

Secondary Treatment (Biological): The primary effluent is passed into large aeration tanks where ‘flocs’ (masses of bacteria and fungi) consume the organic matter.

This significantly reduces the BOD (Biochemical Oxygen Demand) of the water.

Chemistry: Organic & Electrochemistry (लॉन्ग आंसर)

Q5: Explain the ‘Haber’s Process’ for the manufacture of Ammonia with a flow chart.

Detailed Answer: Ammonia is produced by the reaction of Nitrogen and Hydrogen in a 1:3 ratio.

Conditions: High pressure (200 atm), Optimum temperature (700 K), and Iron oxide as a catalyst with Molybdenum as a promoter.

Equation: N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) + Heat.

Geography: World Map & Resources

Q6: Discuss the problems of Indian Agriculture and suggest some measures to improve it.
Problems:

Dependence on Monsoon: Irregular rainfall leads to crop failure.
Small Land Holdings: Most farmers have very small plots, making modern machinery difficult to use.

Lack of Finance: Farmers often fall into debt-traps of local moneylenders.

Solutions: Implementation of ‘Green Revolution’ techniques, providing cheap institutional credit through KCC (Kisan Credit Card), and improving irrigation facilities.

यह विस्तृत अध्ययन सामग्री नर्सिंग ऑफिसर दीपक कुमार द्वारा छात्रों के मार्गदर्शन हेतु तैयार की गई है। इसमें बोर्ड के ‘लॉन्ग आंसर’ पैटर्न का विशेष ध्यान रखा गया है। © Bexyhub.in

Physics: Electromagnetic Induction & Atom

Q7: Explain the construction and principle of an AC Generator.

Principle: It works on the principle of Faraday’s Law of Electromagnetic Induction.

When a coil is rotated in a uniform magnetic field, the magnetic flux linked with the coil changes, inducing an EMF.

Construction: It has four main parts—Armature (coil), Field Magnets, Slip Rings, and Brushes.

Working: As the coil rotates, the angle \theta changes, and the induced EMF is given by e = NBA\omega \sin(\omega t)

Q8: State the postulates of Bohr’s Model of an Atom.
Answer:

Electrons revolve in discrete orbits called ‘Stationary Orbits’ without radiating energy.

The angular momentum of an electron is quantized: mvr = nh/2\pi.

Energy is emitted or absorbed only when an electron jumps from one orbit to another (E_2 – E_1 = hf).

Chemistry: Coordination Compounds & Biomolecules

Q9: What is Crystal Field Theory (CFT)? Explain the splitting of d-orbitals in an Octahedral complex.

Detailed Answer: CFT considers the bond between metal and ligand to be purely electrostatic.

In an octahedral field, the five degenerate d-orbitals split into two sets: {2g} (lower energy) and e_g (higher energy).

The energy difference between these sets is called Crystal Field Splitting Energy  Delta

Q10: Classify Carbohydrates on the basis of their behavior towards hydrolysis.
Answer:

Monosaccharides: Cannot be further hydrolyzed (e.g., Glucose, Fructose).

Oligosaccharides: Give 2 to 10 monosaccharide units (e.g., Sucrose, Lactose).

Polysaccharides: Give a large number of monosaccharide units (e.g., Starch, Cellulose).

Economics: National Income & Government Budget

Q11: Explain the three methods of calculating National Income.

Value Added Method: Sum of GVA at MP of all producing sectors.

Income Method: Sum of factor incomes (Compensation of Employees + Operating Surplus + Mixed Income).

Expenditure Method: Sum of final expenditures (Private Consumption + Govt Consumption + Investment + Net Exports).

Q12: What are the objectives of a Government Budget?
Answer:

1. Reallocation of Resources (Taxing luxury goods and subsidizing essentials).

2. Reducing inequalities in income.

3. Economic stability (controlling inflation/deflation).

4. Management of Public Enterprises.

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