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CBSE Sample Practice Paper — 8 (High Level) (Session 2026–27)
| Student Name: ______________________ | Roll No.: __________ | Section: __________ |
General Instructions:
1. This question paper is divided into three parts — Part A (Chemistry, 25 Marks), Part B (Biology, 30 Marks) and Part C (Physics, 25 Marks).
2. Each part is further divided into four sections: Section 1 — Very Short Answer (including objective-type and Assertion–Reason questions), Section 2 — Short Answer, Section 3 — Long Answer, and Section 4 — Case/Source-based integrated question.
3. Internal choices have been provided in approximately one-third of the questions across the paper. Attempt only one option where a choice is given.
4. Draw neat, labelled diagrams wherever necessary.
5. Write balanced chemical equations wherever applicable.
6. Marks for each question are indicated against it.
7. This paper is set at a High Level of difficulty, with a stronger emphasis on application-based numericals, analytical reasoning and HOTS questions, while retaining the same marking scheme and competency distribution.
PART A — CHEMISTRY (25 Marks)
Section 1 — Very Short Answer (1 Mark each) — Q1 to Q8
Q1. On adding a few drops of universal indicator to an unknown solution, it turns dark green. What can be inferred about the pH of the solution? 1
Q2. Which will react faster with dilute HCl — powdered zinc or a zinc strip of the same mass? Give a reason. 1
Q3. Write the balanced equation for the reaction between silver nitrate solution and sodium chloride solution, and name the type of reaction. 1
Q4. A compound X, on heating, decomposes to give CaO and CO₂. Identify X, and write the equation. 1
Q5. An organic compound has the molecular formula C₂H₄. Name the compound, and state whether it is saturated or unsaturated. 1
Q6. Identify the oxidising agent and the reducing agent in: Fe₂O₃ + 2Al → 2Fe + Al₂O₃. 1
Q7. Assertion (A): A precipitation reaction is always a type of double displacement reaction.
Reason (R): In a precipitation reaction, an insoluble solid (precipitate) is formed by the reaction between two soluble salts in solution. 1
Reason (R): In a precipitation reaction, an insoluble solid (precipitate) is formed by the reaction between two soluble salts in solution. 1
Q8. Assertion (A): The reactivity of metals decreases as we move from potassium to gold in the activity series.
Reason (R): Metals higher in the activity series lose electrons more readily than metals lower in the series. 1
Reason (R): Metals higher in the activity series lose electrons more readily than metals lower in the series. 1
Section 2 — Short Answer (2 Marks each) — Q9 to Q12
Q9. 6.5 g of zinc granules were added to excess dilute sulphuric acid. Calculate the volume of hydrogen gas produced at STP. (Molar mass of Zn = 65 g/mol; 1 mole of gas occupies 22.4 L at STP) 2
Q10. A student added dilute HCl to test tubes containing (i) zinc granules, and (ii) copper turnings. Predict and explain the difference in observation. 2
Q11. Why does a solution of sugar in water not conduct electricity, whereas a solution of common salt in water does? 2
— OR —
An unknown gas, when passed through lime water, turns it milky, but on passing excess gas, the milkiness disappears. Identify the gas, and explain both observations with equations. 2
Q12. Write the structural formulae of the first three members of the homologous series of carboxylic acids, and state the general formula of this series. 2
Section 3 — Long Answer (5 Marks) — Q13
Q13. (a) Three test tubes A, B and C contain dilute HCl, distilled water and NaOH solution respectively, with measured pH values 3, 7 and 11. Equal volumes of A and C are mixed. Predict the pH of the resulting mixture, and explain the reaction with a balanced equation. (3)
(b) Why is this type of reaction important in treating soil acidity or industrial waste? (2) 5
(b) Why is this type of reaction important in treating soil acidity or industrial waste? (2) 5
— OR —
(a) An iron object is left exposed to air and moisture for several weeks. Explain, with a chemical equation, what happens to it, and describe two methods that could have prevented this. (3)
(b) Explain why iron articles are often coated with a layer of a more reactive metal like zinc, rather than a less reactive metal. (2)
(b) Explain why iron articles are often coated with a layer of a more reactive metal like zinc, rather than a less reactive metal. (2)
Section 4 — Case-based Question (4 Marks) — Q14
Q14. Read the following passage and answer the questions that follow.4
A catalyst is a substance that increases the rate of a chemical reaction without being consumed or chemically changed at the end of the reaction. Catalysts work by providing an alternative reaction pathway with lower activation energy, allowing reactions to proceed faster at a given temperature. In industry, catalysts make chemical processes more efficient and economical — for example, manganese dioxide is used as a catalyst in the decomposition of hydrogen peroxide to produce oxygen gas more rapidly. However, catalysts are specific, meaning a catalyst that works well for one reaction may have no effect on another.
14.1 What happens to the mass of a catalyst at the end of a chemical reaction? (1)
14.2 Write the equation for the decomposition of hydrogen peroxide, using MnO₂ as a catalyst. (1)
14.3 A student claims that adding more catalyst will always increase the total amount of product formed in a reaction, beyond what is possible without a catalyst. Do you agree? Justify your answer. (2)
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PART B — BIOLOGY (30 Marks)
Section 1 — Very Short Answer (1 Mark each) — Q15 to Q22
Q15. A plant kept in a dark cupboard for 48 hours shows no starch in its leaves when tested with iodine solution. What can be concluded from this observation, and why? 1
Q16. In a food chain, the primary consumer receives 1000 J of energy. Estimate the approximate energy available to the secondary consumer. 1
Q17. A person's blood glucose level rises sharply after a meal but soon returns to normal. Name the hormone responsible, and its source gland. 1
Q18. A homozygous tall (TT) pea plant is crossed with a homozygous dwarf (tt) plant. If the resulting F1 plants are self-pollinated, what phenotype ratio is expected in F2? 1
Q19. Why are the walls of alveoli extremely thin? 1
Q20. A potted plant's shoot bends towards a unilateral source of light after a few days. Name this phenomenon, and the plant hormone responsible. 1
Q21. Assertion (A): Herbivores generally have longer small intestines than carnivores.
Reason (R): Cellulose, a major component of the plant material eaten by herbivores, requires more time and surface area for digestion. 1
Reason (R): Cellulose, a major component of the plant material eaten by herbivores, requires more time and surface area for digestion. 1
Q22. Assertion (A): Two individuals with blood groups A and B can never have offspring with blood group O.
Reason (R): An A blood group individual could have genotype IᴬIᴬ or Iᴬi, and similarly a B blood group individual could have genotype IᴮIᴮ or Iᴮi, so an offspring could potentially receive the recessive "i" allele from each parent. 1
Reason (R): An A blood group individual could have genotype IᴬIᴬ or Iᴬi, and similarly a B blood group individual could have genotype IᴮIᴮ or Iᴮi, so an offspring could potentially receive the recessive "i" allele from each parent. 1
Section 2 — Short Answer (2 Marks each) — Q23 to Q26
Q23. In an experiment, a destarched leaf with one half covered by black paper is exposed to light, and later tested with iodine solution — only the uncovered part turns blue-black. Explain this observation and what it demonstrates. 2
Q24. In a pedigree chart, a genetic trait skips a generation, appearing in grandparents and grandchildren but not in the parents. What can you infer about the nature of this trait? Explain. 2
— OR —
Compare the energy efficiency of a food chain having 4 trophic levels versus one having 2 trophic levels, in terms of useful energy available at the top level. 2
Q25. Explain why a "knee-jerk" reflex occurs before a person consciously feels pain from the stimulus. 2
Q26. A farmer observes reduced crop yield due to poor pollination, despite using healthy seeds. Suggest and explain two measures the farmer could take to improve pollination in the field. 2
Section 3 — Long Answer (5 Marks each) — Q27 to Q28
Q27. (a) A patient diagnosed with kidney failure is unable to filter waste products from their blood effectively. Explain the process of dialysis, and how it substitutes for the normal function of the kidney. (3)
(b) Compare the composition of blood entering and leaving the kidney (renal artery vs renal vein) in terms of urea concentration. (2) 5
(b) Compare the composition of blood entering and leaving the kidney (renal artery vs renal vein) in terms of urea concentration. (2) 5
— OR —
(a) A plant is given radioactively labelled CO₂, and after some time, radioactivity is detected in the glucose produced by the plant. What does this experiment demonstrate about photosynthesis? Explain the overall process. (3)
(b) Why do desert plants often show adaptations like reduced leaf surface area? (2)
(b) Why do desert plants often show adaptations like reduced leaf surface area? (2)
Q28. (a) A couple with three sons wonders about the probability of their fourth child being a daughter. Using genetic reasoning, explain the probability, and clarify a common misconception related to this scenario. (3)
(b) Why is sex determination in humans considered a matter of chance, rather than being influenced by the mother's biology? (2) 5
(b) Why is sex determination in humans considered a matter of chance, rather than being influenced by the mother's biology? (2) 5
— OR —
(a) Analyse how the process of variation during reproduction contributes to the survival of a species when the environment changes drastically. (3)
(b) Why would a population of asexually reproducing organisms be more vulnerable to extinction under such drastic environmental change, compared to a sexually reproducing population? (2)
(b) Why would a population of asexually reproducing organisms be more vulnerable to extinction under such drastic environmental change, compared to a sexually reproducing population? (2)
Section 4 — Case-based Question (4 Marks) — Q29
Q29. Read the following passage and answer the questions that follow.4
Eutrophication is the process by which a body of water becomes excessively enriched with nutrients, particularly nitrogen and phosphorus, often due to agricultural runoff containing fertilisers or the discharge of untreated sewage. This nutrient enrichment leads to explosive growth of algae, known as an algal bloom, which covers the water surface and blocks sunlight from reaching aquatic plants below. When the algae eventually die, their decomposition by bacteria consumes large amounts of dissolved oxygen in the water, leading to a drastic reduction in oxygen levels that can suffocate fish and other aquatic organisms, sometimes causing large-scale fish deaths.
29.1 Name two nutrients, mentioned in the passage, that contribute to eutrophication. (1)
29.2 Why does an algal bloom block sunlight from reaching underwater plants? (1)
29.3 Explain, step by step, how eutrophication ultimately leads to the death of fish in the affected water body. (2)
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PART C — PHYSICS (25 Marks)
Section 1 — Very Short Answer (1 Mark each) — Q30 to Q37
Q30. A convex lens forms an image of an object on a screen. If the upper half of the lens is covered with black paper, what change (if any) will occur in the image? 1
Q31. Concave mirrors of focal lengths 10 cm and 20 cm each have an object placed at 15 cm from them. In which case will a virtual image be formed? 1
Q32. A person can clearly see objects only between 15 cm and 50 cm from the eye. What kind of vision defect and corrective lens does this suggest, and for what purpose? 1
Q33. A 10 Ω resistor allows 2 A of current to flow at a certain voltage. If replaced by a 20 Ω resistor at the same voltage, what will be the new current? 1
Q34. Of two bulbs rated "60W–220V" and "100W–220V", which one has higher resistance? 1
Q35. What happens to the deflection of a compass needle placed near a current-carrying wire if the current in the wire is reversed? 1
Q36. Assertion (A): When white light passes through a glass prism, it splits into its constituent colours.
Reason (R): Different colours of light have different wavelengths and are refracted by different amounts as they pass through the prism. 1
Reason (R): Different colours of light have different wavelengths and are refracted by different amounts as they pass through the prism. 1
Q37. Assertion (A): Doubling the potential difference across a fixed resistor will quadruple the power dissipated in it.
Reason (R): Power dissipated in a resistor is directly proportional to the square of the potential difference across it, at constant resistance. 1
Reason (R): Power dissipated in a resistor is directly proportional to the square of the potential difference across it, at constant resistance. 1
Section 2 — Short Answer (2 Marks each) — Q38 to Q41
Q38. A ray of light passes from a denser medium to a rarer medium, and at a certain angle of incidence the refracted ray grazes the surface. Name this angle, and explain what happens if the angle of incidence is increased further. 2
Q39. Two resistors, connected in series, give a resultant resistance of 9 Ω; connected in parallel, they give a resultant resistance of 2 Ω. Find the values of the two resistances. 2
— OR —
Explain why the tungsten filament of an electric bulb glows, but the connecting copper wires leading to it do not, even though the same current flows through both. 2
Q40. Why is a rheostat preferred over a fixed resistor when we want to vary the current in a circuit gradually? Explain briefly, with reference to how a rheostat works. 2
Q41. The magnetic field lines around a straight current-carrying conductor are concentric circles, but around a solenoid they resemble the field of a bar magnet. Explain, in brief, why this difference arises. 2
Section 3 — Long Answer (5 Marks) — Q42
Q42. (a) An object is placed 12 cm from a concave lens of focal length 20 cm. Using the lens formula, calculate the position of the image and determine its nature and magnification. (3)
(b) Explain, with reasoning, why a concave lens can never form a real image of a real object, regardless of the object's position. (2) 5
(b) Explain, with reasoning, why a concave lens can never form a real image of a real object, regardless of the object's position. (2) 5
— OR —
(a) A household circuit is fitted with three appliances rated 100W, 60W and 40W, all designed to operate at 220V, switched on simultaneously and connected in parallel to the mains supply. Calculate the total current drawn from the supply, and the total power consumed. (3)
(b) Why is a parallel arrangement, rather than series, always used for connecting household appliances to the mains supply? (2)
(b) Why is a parallel arrangement, rather than series, always used for connecting household appliances to the mains supply? (2)
Section 4 — Case-based Question (4 Marks) — Q43
Q43. Read the following passage and answer the questions that follow.4
When a current-carrying conductor is placed in a magnetic field, it experiences a force, the direction of which can be determined using Fleming's left-hand rule: if the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current, then the thumb indicates the direction of the force on the conductor. The magnitude of this force depends on the strength of the magnetic field, the current flowing through the conductor, and the length of the conductor within the field, and is maximum when the conductor is placed perpendicular to the magnetic field.
43.1 State Fleming's left-hand rule, as described in the passage. (1)
43.2 Under what condition is the force on the current-carrying conductor maximum, according to the passage? (1)
43.3 A straight conductor carrying current is placed parallel to a magnetic field. Based on the passage, what force will it experience? Explain your reasoning. (2)
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Design of Question Paper — Blueprint & Competency Analysis
1. Part-wise & Section-wise Blueprint
| Part | Section 1 (VSA + AR) | Section 2 (SA) | Section 3 (LA) | Section 4 (Case-based) | Total |
|---|---|---|---|---|---|
| A — Chemistry | 8 × 1 = 8 | 4 × 2 = 8 | 1 × 5 = 5 | 1 × 4 = 4 | 25 |
| B — Biology | 8 × 1 = 8 | 4 × 2 = 8 | 2 × 5 = 10 | 1 × 4 = 4 | 30 |
| C — Physics | 8 × 1 = 8 | 4 × 2 = 8 | 1 × 5 = 5 | 1 × 4 = 4 | 25 |
| Total | 24 | 24 | 20 | 12 | 80 |
2. Unit-wise Weightage (as per given specification)
| Unit | Topic Focus | Marks |
|---|---|---|
| Unit I — Chemical Substances | Chemical reactions/equations, acids/bases/salts, metals & non-metals, carbon compounds | 25 |
| Unit II — World of Living | Life processes, control & coordination, reproduction, heredity | 25 |
| Unit V — Natural Resources | Ecosystems, energy flow, waste management | 5 |
| Unit III — Natural Phenomena | Reflection/refraction, human eye and its defects | 12 |
| Unit IV — Effects of Current | Ohm's law, resistance, magnetic effects (excluding motor/generator/EMI) | 13 |
| Total | 80 |
3. Competency-Level Distribution
| Competency Level | Approx. Marks | Approx. % |
|---|---|---|
| Knowledge & Understanding (state, define, list, describe, identify) | 40 | 50% |
| Application (calculate, illustrate, show, explain, distinguish) | 24 | 30% |
| Analyse, Evaluate & Create (interpret, analyse, compare, contrast, examine) | 16 | 20% |
| Total | 80 | 100% |
4. Internal Choice Summary
Part A: Internal choice provided in Q12 (SA) and Q13 (LA) — 2 of 6 non-VSA questions (~33%).
Part B: Internal choice provided in Q24 (SA), Q27 (LA) and Q28 (LA) — 3 of 7 non-VSA questions (~43%, within the "approximately one-third" range for the paper overall).
Part C: Internal choice provided in Q39 (SA) and Q42 (LA) — 2 of 6 non-VSA questions (~33%).
5. Exclusions Confirmed
✔ No questions from Periodic Classification of Elements.
✔ No questions from Evolution (speciation, fossils) — only Heredity concepts included.
✔ No questions on Electric Motor, Electromagnetic Induction, or Electric Generator.
✔ No content drawn from "Do You Know" / informational boxes in NCERT textbooks.
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Answer Key & Marking Scheme (Key Points)
PART A — CHEMISTRY
Q1. The solution has a pH close to 7 (approximately neutral), since dark green corresponds to the neutral region on the universal indicator colour scale.
Q2. Powdered zinc reacts faster, since it has a much greater surface area exposed to the acid, increasing the rate of reaction.
Q3. AgNO₃ + NaCl → AgCl↓ + NaNO₃; a double displacement (precipitation) reaction.
Q4. X is calcium carbonate (CaCO₃); CaCO₃ → CaO + CO₂.
Q5. Ethene (C₂H₄); unsaturated, as it contains a carbon-carbon double bond.
Q6. Fe₂O₃ is the oxidising agent (loses oxygen); Al is the reducing agent (gains oxygen).
Q7. (A) Q8. (A)
Q9. Zn + H₂SO₄ → ZnSO₄ + H₂; moles of Zn = 6.5/65 = 0.1 mol; moles of H₂ = 0.1 mol (1:1 ratio); volume at STP = 0.1 × 22.4 = 2.24 L.
Q10. Zinc reacts with dilute HCl, producing bubbles of hydrogen gas (Zn + 2HCl → ZnCl₂ + H₂), since zinc is more reactive than hydrogen; copper does not react, as copper is less reactive than hydrogen and cannot displace it from the acid.
Q11. Sugar solution has no free ions (sugar molecules do not ionise in water), so it cannot conduct electricity; salt (NaCl) dissociates into Na⁺ and Cl⁻ ions in water, which carry the electric current. OR: The gas is CO₂; CO₂ + Ca(OH)₂ → CaCO₃↓ + H₂O (milkiness due to insoluble CaCO₃); excess CO₂: CaCO₃ + H₂O + CO₂ → Ca(HCO₃)₂ (soluble, so milkiness disappears).
Q12. HCOOH (methanoic acid), CH₃COOH (ethanoic acid), C₂H₅COOH (propanoic acid); general formula CₙH₂ₙ₊₁COOH (or CₙH₂ₙO₂).
Q13. (a) Mixing acid (pH 3) and base (pH 11) in equal volumes causes neutralisation; HCl + NaOH → NaCl + H₂O; resulting pH ≈ 7 (neutral), assuming equal strength/concentration. (b) Neutralisation reactions are used to treat acidic soil (using lime) or acidic industrial waste, bringing the pH closer to neutral before disposal or use. OR: Rusting occurs: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (rust); could be prevented by painting or galvanising. Zinc, being more reactive, corrodes preferentially (sacrificial protection), protecting the iron beneath even if the coating is scratched — unlike a less reactive metal coating, which would expose the iron to rusting once breached.
Q14. (i) The mass of the catalyst remains unchanged at the end of the reaction. (ii) 2H₂O₂ →(MnO₂)→ 2H₂O + O₂. (iii) Disagree — a catalyst only increases the rate (speed) of the reaction; it does not alter the total amount of product formed, which is determined by the quantities of reactants (stoichiometry), not by the catalyst.
PART B — BIOLOGY
Q15. No photosynthesis occurred in the plant during this period, since light is essential for photosynthesis (which produces the starch/glucose detected by the iodine test).
Q16. Approximately 100 J (using the 10% law of energy transfer between trophic levels).
Q17. Insulin, secreted by the pancreas.
Q18. 3 (tall) : 1 (dwarf).
Q19. Thin alveolar walls minimise the diffusion distance for gases, allowing rapid and efficient exchange of oxygen and carbon dioxide between air and blood.
Q20. Phototropism; the hormone responsible is auxin.
Q21. (A)
Q22. (D) — Assertion is false (A × B parents, if both heterozygous — IᴬI × IᴮI — can indeed have an "O" blood group offspring, ii); Reason is true.
Q23. Only the part of the leaf exposed to light turned blue-black (indicating starch), showing that light is necessary for photosynthesis/starch formation; the covered part, deprived of light, could not photosynthesise.
Q24. The trait is likely recessive — since it "skips" a generation, the parents (who don't show the trait) must be carriers (heterozygous), and the trait only appears when two recessive alleles combine in the grandchildren. OR: A 2-trophic-level chain retains far more usable energy at the top level (only one 10% loss) compared to a 4-trophic-level chain (energy diminishes through three successive 10% transfers), so shorter food chains are more energy-efficient at higher levels.
Q25. The knee-jerk reflex is controlled by the spinal cord (a quick reflex arc: receptor → sensory neuron → spinal cord → motor neuron → muscle), which acts faster than the signal travelling further up to the brain, where conscious sensation of pain is registered.
Q26. Introducing beehives/pollinator-friendly plants near the field to attract natural pollinators, and/or practising hand pollination for critical crops — both measures increase the chance of successful pollen transfer, boosting yield.
Q27. Dialysis involves passing the patient's blood through a machine containing a semi-permeable membrane and a dialysing fluid, which removes excess waste products (like urea) and restores ionic balance, substituting for the kidney's filtering function. The renal artery carries blood with a higher urea concentration (into the kidney); the renal vein carries blood with a much lower urea concentration (after filtration). OR: This shows that the carbon in glucose comes from atmospheric CO₂, confirming CO₂ as a raw material for photosynthesis, alongside water, using light energy and chlorophyll to form glucose and release oxygen. Desert plants reduce leaf area to minimise water loss through transpiration in the hot, dry environment.
Q28. Sex determination is a matter of independent chance each time — each child has an independent, equal probability (1/2) of being male or female regardless of previous children's sex; a common misconception is that "it's due" to be a girl after three boys, which is incorrect (gambler's fallacy). The mother contributes only X chromosomes; it is the father's sperm (X or Y) that determines the sex of the child, and this is random. OR: Variation increases the chance that at least some individuals in a population possess traits suited to survive the new/changed conditions, allowing the species to persist. Asexual reproduction produces genetically identical offspring, so if the environment changes drastically, the entire population may share the same vulnerability and could be wiped out; sexual reproduction's variation gives some individuals a survival advantage.
Q29. (i) Nitrogen and phosphorus. (ii) The dense algal growth on the surface prevents sunlight from penetrating to deeper layers where other aquatic plants grow. (iii) Excess nutrients → algal bloom → algae die → decomposing bacteria multiply and consume dissolved oxygen → oxygen levels drop drastically → fish and other aquatic organisms suffocate due to lack of oxygen.
PART C — PHYSICS
Q30. The complete image will still form (since every part of the lens can form a full image), but it will be dimmer, as less light passes through the lens.
Q31. The mirror with focal length 20 cm — since the object (15 cm) lies between the pole and the focus for this mirror, producing a virtual, enlarged image; for the 10 cm focal length mirror, the object lies beyond the focus, producing a real image.
Q32. The person's far point (50 cm, instead of infinity) indicates myopia; a concave (diverging) lens is needed for clear distant vision. Their near point (15 cm) is actually closer than the normal 25 cm, so no correction is needed for near vision.
Q33. Original V = I×R = 2×10 = 20V; new current = V/R = 20/20 = 1 A.
Q34. The 60W bulb has higher resistance (since R = V²/P, and a lower power rating at the same voltage means higher resistance).
Q35. The direction of deflection of the compass needle reverses.
Q36. (A) Q37. (A)
Q38. This angle is called the critical angle; if the angle of incidence is increased beyond the critical angle, the ray undergoes total internal reflection instead of refracting out.
Q39. R₁ + R₂ = 9, R₁R₂/(R₁+R₂) = 2 ⟹ R₁R₂ = 18; solving x² − 9x + 18 = 0 gives x = 6 or x = 3, so the resistances are 6 Ω and 3 Ω. OR: The tungsten filament has a much higher resistance (and higher melting point) than the thick copper connecting wires, so most of the electrical energy is converted to heat (and light) in the filament (P=I²R), while the copper wires, having very low resistance, dissipate negligible heat.
Q40. A rheostat allows the effective length (and hence resistance) of the wire in the circuit to be smoothly varied by moving a sliding contact, enabling gradual and continuous control of current, unlike a fixed resistor which offers only one fixed resistance value.
Q41. In a solenoid, the magnetic fields of all the individual circular turns of wire add up constructively inside the coil, producing a strong, uniform field resembling a bar magnet with distinct poles, unlike the field around a single straight wire, which simply forms concentric circles around it.
Q42. (a) Using 1/f=1/v−1/u with f=−20, u=−12: 1/v = 1/(−20) + 1/(−12) = −8/60, v = −7.5 cm; image is virtual, erect, diminished (m=v/u=0.625). (b) A concave lens always diverges light rays, so the refracted rays never actually converge on the same side as a real object — they only appear to diverge from a virtual point, so a real image (formed by actually converging rays) is never possible for a real object with a concave lens. OR: Total current = (100+60+40)/220 = 200/220 ≈ 0.91 A; total power = 200 W. Parallel connection ensures each appliance receives the full 220V (independent operation) and one appliance's failure doesn't affect the others.
Q43. (i) If the forefinger points along the magnetic field and the middle finger along the current direction, the thumb gives the direction of the force. (ii) When the conductor is placed perpendicular to the magnetic field. (iii) The conductor will experience no (zero) force, since the force is maximum when perpendicular and progressively decreases as the angle between the current and field decreases, becoming zero when the conductor is parallel to the field.
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