The PDF shows 42 questions (21 wrong, 21 blank), which gives 531. The reported 526 means one more wrong answer that is not in the PDF — so one section is 5 marks lower than shown.
2. Error families
Family
Questions
Count
Marks lost
Blank — statement type
Q52, Q86, Q98, Q102, Q112, Q121, Q148
7
28
Blank — formula not attempted
Q3, Q12, Q19, Q21, Q24, Q25, Q28, Q173
8
32
Blank — recall
Q59, Q157, Q172
3
12
Blank — match type
Q67
1
4
Blank — A–R type
Q169
1
4
Blank — not attempted
Q110
1
4
Factor / scaling slip
Q13, Q17, Q20, Q22, Q125, Q134
6
30
Ratio / direction reversal
Q30, Q73, Q171, Q168, Q180
5
25
Concept gap
Q7, Q10, Q32, Q144
4
20
NCERT fact
Q90, Q117, Q138, Q178
4
20
Arrangement / order
Q54, Q107
2
10
3. What the paper says
Biology leaked the most, not Physics. Botany 140 and Zoology 130 against 165 targets — 90 marks lost across 90 Biology questions. Physics (112) was only 8 short and Chemistry (149) was on target.
Statement and A–R questions are now being left blank. 11 of the 42 errors are two-statement or A–R questions, and 8 of those were blanks — Q52, 86, 98, 102, 112, 121, 148, 169. After the A–R drill she is avoiding them instead of applying the three steps. Most were unchanged NCERT lines worth +4 each.
Physics blanks are one missing formula sheet. Four Magnetism & Matter numericals (Q21, 24, 25, 28) all need the bar-magnet equatorial/axial formulas or the sum–difference magnetometer rule.
Factor-of-2 and scaling slips cost 30 marks (Q13, 17, 20, 22, 125, 134) — the known ratio/scaling family, now showing in Biology crosses too.
Repeat misses: starch grain (Q102, 5th time), Hardy–Weinberg (Q173, again after the Evolution paper), match rows swapped (Q107), attribution (Q121, Q138).
4. Question by question
Physics — 8 wrong · 7 blank
Moving Charges and Magnetism
Q3BlankTBlank — formula not attemptedLorentz force (E and B together)
E = (2î − 3ĵ) N/C and B = (5î + 3ĵ + 4k̂) T. Force on a 1 C charge moving with v = (î + 2ĵ) m/s?
Where it went wrong · fixSkipped because the cross product looked long. It is a 40-second determinant.
Q7WrongCConcept gapForce on a bent wire in uniform B
Wire PQ (4 cm up, 6 cm right, 4 cm up) carries 10 A in a uniform 5 T field out of the page. Net force?
Her answer0
Correct answer5 N
WhyIn a uniform field the force on any shaped wire equals the force on the straight line joining its ends. PQ: horizontal 6 cm, vertical 4 + 4 = 8 cm, so L_eff = √(6² + 8²) = 10 cm. F = BIL = 5 × 10 × 0.10 = 5 N.
Where it went wrong · fixZero is only for a CLOSED loop. An open wire never gives zero unless its two ends coincide.
Q10WrongCConcept gapTension in a current loop
A circular wire of radius R carrying current i lies in a field B perpendicular to its plane. Tension along the wire?
Her answer2πBiR
Correct answerBiR
WhyTake half the ring. Net magnetic force on a semicircle = Bi × (chord) = Bi(2R). It is balanced by the tension at the two cut ends: 2T = 2BiR, so T = BiR.
Where it went wrong · fix2πBiR adds up force magnitudes around the whole circle — that is not tension, and the vector sum on a full loop is actually zero.
Q12BlankTBlank — formula not attemptedForce between parallel currents
Two wires 5 cm apart carry equal opposite currents; the upper wire (10 cm, 5 g) floats. Current?
Her answerLeft blank
Correct answer350 A
WhyOpposite currents repel, so the magnetic force holds the upper wire up: μ₀I²L / (2πd) = mg. I² = mg·2πd / (μ₀L) = 0.005 × 9.8 × 2π × 0.05 / (4π×10⁻⁷ × 0.1) = 1.225 × 10⁵, so I = 350 A.
Where it went wrong · fixStandard one-line balance — write F/L = μ₀I₁I₂/(2πd) first, then equate to mg.
Q13WrongSFactor / scaling slipRatio B/M under scaling
Ratio of field at the centre of a coil to its magnetic moment is x. Current and radius are both doubled. New ratio?
Her answerx/4
Correct answerx/8
WhyB/M = (μ₀I/2R) / (IπR²) = μ₀ / (2πR³). Current cancels; R doubled divides the ratio by 2³ = 8.
Where it went wrong · fixScaled by R² only (from the area). Write the full ratio and cancel before plugging in.
Q17WrongSFactor / scaling slipWork to rotate a coil
Coil: r = 4 cm, 50 turns, 2 A, in 0.1 Wb/m². Work to rotate it 180° from equilibrium?
Her answer0.2 J
Correct answer0.1 J
WhyM = NIA = 50 × 2 × π(0.04)² = 0.503 A·m². W = MB(cos 0° − cos 180°) = 2MB = 2 × 0.503 × 0.1 = 0.10 J.
Where it went wrong · fix0.2 J comes from doubling twice (4MB). The factor 2 comes only once, from (1 − cos 180°).
Q19BlankTBlank — formula not attemptedGalvanometer sensitivities
Current sensitivity 25 div/mA, voltage sensitivity 125 div/V. Resistance of the galvanometer?
Her answerLeft blank
Correct answer200 Ω
WhyVoltage sensitivity = current sensitivity / R, so R = Is / Vs. Convert first: 25 div/mA = 25 000 div/A. R = 25 000 / 125 = 200 Ω.
Where it went wrong · fixThe mA-to-A conversion is the only step; without it you get 0.2 Ω, which is not an option — a signal to recheck units.
Q20WrongSFactor / scaling slipTorsion constant of a galvanometer
Coil 5 cm², 100 turns, 0.5 × 10⁻⁴ A, in 2000 G, deflects 20°. Couple per unit twist?
Her answer5 × 10⁻⁸ N·m/degree
Correct answer2.5 × 10⁻⁸ N·m/degree
WhyNIAB = kθ. Convert: A = 5 × 10⁻⁴ m², B = 2000 G = 0.2 T. k = 100 × 0.5×10⁻⁴ × 5×10⁻⁴ × 0.2 / 20 = 2.5 × 10⁻⁸ N·m/degree.
Where it went wrong · fixDivided by 10 instead of 20 — a factor-of-2 slip at the last step.
Magnetism and Matter
Q21BlankNBlank — formula not attemptedMagnetic moment of a bent strip
A 5 cm strip with M = 0.5 A·m² is bent so its ends are 1 cm apart. New magnetic moment?
Her answerLeft blank
Correct answer0.1 A·m²
WhyM = m × (distance between poles). Pole strength m is unchanged by bending; only the pole separation changes from 5 cm to 1 cm. M′ = 0.5 × (1/5) = 0.1 A·m².
Where it went wrong · fixRule: bending never changes m — only the straight-line distance between the ends.
Q22WrongSFactor / scaling slipField midway between two poles
Horseshoe magnet: poles of strength 4 A·m, 4 cm apart. Field at the midpoint?
Her answer10⁻³ T
Correct answer2 × 10⁻³ T
WhyEach pole at r = 2 cm: B = (μ₀/4π) m/r² = 10⁻⁷ × 4 / (0.02)² = 10⁻³ T. At the midpoint both fields point from N to S — the same direction — so they add: 2 × 10⁻³ T.
Where it went wrong · fixCounted one pole only. Always ask: do the two contributions add or cancel here?
Q24BlankTBlank — formula not attemptedNeutral point, N-pole pointing north
Bar magnet 10 cm, N-pole pointing north. Neutral point 15 cm from each pole. B_H = 0.4 G. Pole strength?
Her answerLeft blank
Correct answer13.5 A·m
WhyN-pole north puts the neutral points on the equatorial line. There B = (μ₀/4π) m(2l)/d³ with d = 15 cm (distance to each pole), 2l = 10 cm. 0.4 × 10⁻⁴ = 10⁻⁷ × m × 0.1 / (0.15)³, so m = 13.5 A·m.
Where it went wrong · fixKey fact: N pointing north → equatorial; N pointing south → axial.
Q25BlankTBlank — formula not attemptedField at the vertex of an equilateral triangle
Magnet (10 cm, M = 1 A·m²) along side AB of an equilateral triangle of side 10 cm. Field at C?
Her answerLeft blank
Correct answer10⁻⁴ T
WhyC is equidistant from both poles, so it is an equatorial point with pole distance d = 10 cm. B = (μ₀/4π) M/d³ = 10⁻⁷ × 1 / (0.1)³ = 10⁻⁴ T.
Where it went wrong · fixSame equatorial formula as Q24 — two blanks from one missing formula.
Q28BlankTBlank — formula not attemptedVibration magnetometer, sum and difference
Two magnets: like poles together T = 10 s; unlike poles together T = 20 s. Ratio of moments?
Her answerLeft blank
Correct answer5 : 3
WhyT ∝ 1/√M. Like poles together → M₁ + M₂ (T = 10 s); unlike → M₁ − M₂ (T = 20 s). (20/10)² = (M₁ + M₂)/(M₁ − M₂) = 4, so M₁ = (5/3)M₂ → 5 : 3.
Where it went wrong · fixThe longer period belongs to the smaller moment (the difference).
Q30WrongSRatio / direction reversalEquilibrium of crossed magnets
Magnets M and M√3 joined at right angles in a uniform field B. θ for equilibrium?
Her answer30°
Correct answer60°
WhyTorques balance: MB sin θ = (M√3) B sin(90° − θ), so tan θ = √3 and θ = 60°.
Where it went wrong · fix30° is tan θ = 1/√3 — the ratio written upside-down. Mark which angle θ is on the figure before writing the torques.
Q32WrongCConcept gapTime period after cutting a magnet
A bar magnet of period T is cut into four equal parts (perpendicular to length and breadth). Period of each part?
Her answerT/4
Correct answerT/2
WhyEach piece: mass m/4, length and breadth halved → I′ = (m/4)(L²/4 + b²/4)/12 = I/16. Pole strength halves and length halves → M′ = M/4. T ∝ √(I/M) → √((1/16)/(1/4)) = 1/2 → T/2.
Where it went wrong · fixScaled only one quantity. Always scale BOTH I and M, then take the square root.
Chemistry — 3 wrong · 4 blank
Coordination Compounds
Q52BlankNBlank — statement typeIonisable chloride
I: [Cr(NH₃)₄Cl₂]Cl precipitates 2 mol AgCl. II: it has two ionisable chloride ions.
Her answerLeft blank
Correct answerBoth statements incorrect
WhyOnly the Cl outside the square bracket ionises. [Cr(NH₃)₄Cl₂]Cl gives one Cl⁻, so 1 mol AgCl. Both statements are false.
Where it went wrong · fixCount Cl outside [ ] only — ligand Cl never precipitates.
Q54WrongCArrangement / orderStability order by Δo / CFSE
Increasing stability based on Δo: (I) [Mn(CN)₆]³⁻ (II) [Co(CN)₆]⁴⁻ (III) [Fe(CN)₆]⁴⁻ (IV) [Fe(CN)₆]³⁻
Her answerII < III < I < IV
Correct answerI < II < IV < III
WhyAll CN⁻ (strong field, low spin), so compare CFSE: Mn³⁺ d⁴ t₂g⁴ = −1.6Δo; Co²⁺ d⁷ t₂g⁶e_g¹ = −1.8Δo; Fe³⁺ d⁵ t₂g⁵ = −2.0Δo; Fe²⁺ d⁶ t₂g⁶ = −2.4Δo. Increasing: I < II < IV < III.
Where it went wrong · fixRanked by oxidation state. Write the d-count and CFSE for each before ordering.
Q59BlankNBlank — recallMononuclear vs polynuclear
Which is not a mononuclear complex?
Her answerLeft blank
Correct answer[Co₂(NH₃)₆(OH)₃]Cl₃
WhyTwo cobalt atoms inside one coordination sphere (bridged by OH) → binuclear. The others have one metal inside the bracket.
Where it went wrong · fixLook at the subscript on the metal inside the bracket.
Q67BlankTBlank — match typeUnpaired electrons (match)
I: Magnetic properties of actinoids are more complex than lanthanoids. II: Actinoids are highly reactive when finely divided.
Her answerLeft blank
Correct answerBoth true
WhyBoth are NCERT lines, unchanged.
Where it went wrong · fixOver-suspicion: two unchanged NCERT lines are a valid answer.
Q90WrongNNCERT factNature of oxides
Nature of V₂O₃ (X) and CrO (Y)?
Her answerX basic, Y amphoteric
Correct answerX basic, Y basic
WhyLowest oxidation state oxides are basic: V₂O₃ (+3) basic, CrO (+2) basic. Cr₂O₃ is amphoteric, CrO₃ acidic; V₂O₅ amphoteric.
Where it went wrong · fixConfused CrO with Cr₂O₃. Rule: oxidation state up → oxide goes basic → amphoteric → acidic.
Botany — 4 wrong · 5 blank
Principles of Inheritance and Variation
Q98BlankNBlank — statement typeConcept of dominance
Which statements are correct: A two alleles per gene; B recessive allele makes a more efficient enzyme; C recessive trait when enzyme is non-functional or absent; D same functional enzyme → same phenotype; E unmodified allele is dominant.
Her answerLeft blank
Correct answerA, C, D and E only
WhyB is false — a modified (recessive) allele gives a less efficient or non-functional enzyme, never a more efficient one. The rest are NCERT lines.
Where it went wrong · fixOne false word ('more efficient') decides the whole question.
Q102BlankNBlank — statement typeStarch grain size — REPEAT MISS
I: The B allele is dominant for seed shape. II: B is incompletely dominant for starch grain size.
Her answerLeft blank
Correct answerBoth correct
WhyOne gene, two expressions: seed shape — round (B) completely dominant; starch grain size — Bb intermediate, so incompletely dominant. Both statements are NCERT.
Where it went wrong · fix5th miss on starch grains. Flashcard: pea starch grain → intermediate → incomplete dominance; seed shape → round wins → complete dominance.
Q107WrongSArrangement / orderMatch: types of dominance
Match complete / incomplete / co-dominance with: F₁ like one parent; intermediate phenotype (snapdragon); both parents expressed (AB).
Her answerA–I, B–III, C–II
Correct answerA–I, B–II, C–III
WhyComplete → F₁ like one parent. Incomplete → intermediate (snapdragon pink). Co-dominance → both expressed (AB blood group).
Where it went wrong · fixRows B and C swapped — right content, wrong arrangement. Her recurring match error.
Q110BlankTBlank — not attemptedPhenotype → genotype
Phenotype predicts genotype exactly in all EXCEPT?
Her answerLeft blank
Correct answerBlood group B
WhyGroup B can be IᴮIᴮ or Iᴮi. Pink snapdragon is always Rr; large starch grains always BB; white pea flowers always recessive homozygous.
Where it went wrong · fixAsk 'can two genotypes give this phenotype?' for each option.
Q112BlankNBlank — statement typeMendel and pink flowers
I: Mendel observed pink F₁ from red × white pea. II: With incomplete dominance the 3:1 ratio deviates in F₂.
Her answerLeft blank
Correct answerI incorrect, II correct
WhyPink F₁ is snapdragon (Correns), not Mendel's pea — Mendel saw complete dominance. II is right: 1 : 2 : 1 instead of 3 : 1.
Where it went wrong · fixAttribution trap: right fact, wrong organism/scientist.
Q117WrongNNCERT factFour statements on dominance
I yellow pod expressed only when homozygous; II law of dominance explains 3:1; III modified allele may make normal enzyme; IV dominance is not autonomous.
Her answerII and III only
Correct answerI, II, III and IV
WhyI: yellow pod is recessive in pea, so only homozygous — true. IV is an NCERT line — true. All four correct.
Where it went wrong · fixOver-suspicion again: rejected true NCERT lines. If you cannot name the false word, the statement is true.
Q121BlankNBlank — statement typeSutton and Boveri
A: Sutton and Boveri rediscovered Mendel's results. R: Sutton and Boveri united chromosomal segregation with Mendelian principles and named it the chromosomal theory.
Her answerLeft blank
Correct answerBoth A and R false
WhyRediscovery (1900) was by de Vries, Correns and von Tschermak. NCERT credits Sutton (alone) with uniting the ideas and naming the chromosomal theory.
Where it went wrong · fixAttribution error family: check every name, not just the idea.
AaBBCc × aabbCc — number of aaBBCc among 512 progeny?
Her answer32
Correct answer0
WhyAt the B locus BB × bb gives only Bb, so no progeny can be BB. aaBBCc is impossible → 0.
Where it went wrong · fixMultiplied probabilities (1/16 × 512 = 32) without checking each locus first. Rule: check every locus can produce the genotype before calculating.
Q134WrongSFactor / scaling slipGamete fraction
Genotype AabbCcdd — percentage of gametes carrying a, b, c, d only?
Her answer50%
Correct answer25%
WhyOnly A and C are heterozygous. P(a) = ½, P(b) = 1, P(c) = ½, P(d) = 1 → ¼ = 25%.
Where it went wrong · fixCounted only one heterozygous locus. Circle every heterozygous pair first.
Zoology — 6 wrong · 5 blank
Evolution
Q138WrongNNCERT factAustralopithecus
Lived in East African grasslands about 2 mya, hunted with stone weapons, essentially ate fruit?
Her answerHomo erectus
Correct answerAustralopithecus
WhyNCERT: about 2 mya, Australopithecines lived in East African grasslands, hunted with stone weapons but essentially ate fruit. Homo erectus came ~1.5 mya, 900 cc brain, probably ate meat.
Where it went wrong · fixAttribution error — timeline card: Dryopithecus/Ramapithecus 15 mya → Australopithecus 2 mya → H. habilis → H. erectus 1.5 mya → Neanderthal → H. sapiens.
Q144WrongCConcept gapHomologous organs
Which are homologous organs?
Her answerButterfly wing and bird wing
Correct answerForelimb bones of whale and cheetah
WhyHomologous = same structure, different function (divergent evolution): whale flipper and cheetah leg share the forelimb bone pattern. Butterfly/bird wings and dolphin/penguin flippers are analogous. The potato option also swaps root and stem.
Where it went wrong · fixPicked the analogous pair. Test: same bones → homologous; same job only → analogous.
Q148BlankNBlank — statement typeGeological and biological history
I: Geological history closely correlates with biological history. II: Rate of appearance of new forms is not linked to life cycle or lifespan.
Her answerLeft blank
Correct answerI correct, II incorrect
WhyNCERT says the rate IS linked to the life cycle or lifespan (microbes evolve faster). The 'not' makes II false.
Where it went wrong · fixSame NCERT line as Q169 — one line, two lost questions.
Q169BlankTBlank — A–R typeA–R: rate of new forms
A: New forms appear faster in microbes than in fish. R: The rate is linked to life cycle or lifespan.
Her answerLeft blank
Correct answerBoth true, R explains A
WhyMicrobes have very short life cycles, so they produce new forms faster. R is the NCERT reason for A.
Where it went wrong · fixThree-step A–R method would have solved it in 20 seconds.
Q171WrongSRatio / direction reversalContinental drift
I: When South America joined North America, some North American fauna were overridden by South American fauna. II: Pouched mammals of Asia survived for lack of competition.
Her answerBoth correct
Correct answerBoth incorrect
WhyNCERT: South American mammals were overridden by North American fauna — I is reversed. Pouched mammals are of Australia, not Asia — II has a planted place name.
Where it went wrong · fixTwo planted swaps (direction and place). Read every proper noun against NCERT.
Q173BlankTBlank — formula not attemptedHardy–Weinberg
Population 800; homozygous recessive 288. Number of heterozygotes?
Where it went wrong · fixHardy–Weinberg skipped again (lost in the Evolution paper too). Write the full row p² · 2pq · q² every time.
Human Health and Disease
Q157BlankNBlank — recallPhysiological barrier
Bactericidal component of tears and saliva?
Her answerLeft blank
Correct answerLysozyme
WhyLysozyme in tears and saliva is part of innate (physiological) barriers.
Where it went wrong · fixPure recall — add to the HHD flashcard deck.
Q168WrongNRatio / direction reversalMain lymphoid organ
The main primary lymphoid organ in the body is?
Her answerThymus
Correct answerBone marrow
WhyNCERT: bone marrow is the main lymphoid organ, where all blood cells including lymphocytes are produced. Thymus is also primary, but 'main' points to bone marrow.
Where it went wrong · fixThe key word is 'main' — two options are primary; only one is the NCERT 'main'.
Q172BlankNBlank — recallFirst antibody
Which antibody is released first after an infection?
Her answerLeft blank
Correct answerIgM
WhyIgM is the first antibody produced in the primary response; IgG follows and dominates the secondary response.
Where it went wrong · fixRecall — IgM = 'M for first' (primary).
Q178WrongNNCERT factPrimary immune response
First encounter with a pathogen produces?
Her answerPrimary response of high intensity
Correct answerPrimary response of low intensity
WhyPrimary response is low intensity; the secondary (anamnestic) response is highly intensified because of memory cells.
Where it went wrong · fixMixed up the two responses. Primary = low, secondary = high.
Q180WrongSRatio / direction reversalHIV — select the INCORRECT statement
Select the incorrect statement about HIV.
Her answerTwo identical single-stranded RNA molecules
Correct answerViral RNA gets incorporated into host DNA
WhyHIV's genome really is two identical ssRNA copies (true). The false statement is the last one: reverse transcriptase makes viral DNA, and it is the DNA that is incorporated into host DNA — not RNA.
Where it went wrong · fixPlanted word (RNA for DNA) plus a 'select INCORRECT' stem. Circle 'incorrect' before reading options.
5. Fix list — carry into every paper
Never leave a two-statement or A–R question blank. Mark T/F beside each statement; if you cannot name the false word, it is true. Expected gain: most of the 8 blanks.
Bar-magnet card: axial B = (μ₀/4π)·2M/r³ · equatorial B = (μ₀/4π)·M/d³ with d = distance to each pole · N-pole north → neutral points equatorial · T ∝ 1/√M, like poles → M₁+M₂, unlike → M₁−M₂.
Before any ratio: write it in full and cancel. Q13 (R³), Q30 (tan θ), Q32 (I and M both scale).
Before multiplying genetics probabilities: check every locus can give the genotype (Q125), and circle heterozygous pairs (Q134).
Match questions: solve all rows in the margin first (Q107, Q67).
Flashcards today: starch grain · lysozyme · IgM first · bone marrow = main lymphoid organ · primary response low / secondary high · Australopithecus 2 mya ate fruit · South America overridden by North American fauna · Australia marsupials · IE₂ Cu > Zn · CrO basic / Cr₂O₃ amphoteric.
Error tags: C concept · N NCERT line · S silly / calculation · T time / not attempted. All numerical answers verified by calculation. Built for errornotes.justsimple.online.