META DESCRIPTIONWBCHSE Class XII Semester III Model Question Bank Part 30 presents a six-subject mega mock examination with Physics and Chemistry numericals, Biology case studies, Mathematics practice, English and Bengali writing tasks, model answers, error analysis and final revision strategies.SEO KEYWORDSWBCHSE Class 12 Semester IIIWBCHSE Model Question Bank Part 30WBCHSE Mega Mock TestClass 12 Full Mock ExaminationWBCHSE Physics PracticeWBCHSE Chemistry PracticeWBCHSE Biological Science QuestionsWBCHSE Mathematics QuestionsWBCHSE English WritingWBCHSE Bengali WritingWBCHSE Case Study QuestionsWBCHSE Competency QuestionsWBCHSE HOTS QuestionsClass 12 Numerical PracticeWBCHSE Final RevisionClass 12 Exam StrategyWBCHSE Self AssessmentHASHTAGS#WBCHSE#Class12#SemesterIII#ModelQuestionBank#MegaMock#FullMockTest#Physics#Chemistry#BiologicalScience#Mathematics#English#Bengali#CaseStudy#CompetencyBasedLearning#HOTS#NumericalPractice#FinalRevision#ExamPreparation#StudentSuccess#Class12Preparation

October 01, 2026

Writing

WBCHSE CLASS XII SEMESTER III

Subject-Wise Model Question Bank — Part 30

MEGA SIX-SUBJECT FINAL MOCK EXAMINATION

Full Mock Papers • Advanced Numericals • Competency-Based Questions • Case Studies • HOTS • English & Bengali Writing • Model Answers • Marking Guidance • Error Analysis • Final Improvement Pathway

INTRODUCTION

Part 30 is a special milestone in this question-bank series.

The purpose of this part is not simply to provide another collection of questions.

It is designed to create an examination-like experience.

The student should now try to move through the complete cycle:

Read → Think → Solve → Write → Check → Analyse → Improve

A student who repeatedly practises this cycle gradually becomes more comfortable with examination pressure.

This part contains six major subject sections:

Physics

Chemistry

Biological Science

Mathematics

English

Bengali

It also includes:

timed practice,

numerical questions,

competency questions,

case studies,

long-answer practice,

writing tasks,

answer-quality checks,

mistake analysis,

and a final revision pathway.

HOW TO USE THIS MEGA MOCK

Before beginning:

STEP 1

Keep your textbook and previous notes away.

STEP 2

Keep a separate answer sheet.

STEP 3

Set a realistic time limit.

STEP 4

Attempt the questions independently.

STEP 5

Do not check answers during the test.

STEP 6

After finishing, compare your answers with the answer key.

STEP 7

Create a mistake list.

PART A — PHYSICS MEGA MOCK

SECTION I — CONCEPTUAL PRACTICE

Q1.

Define electric potential difference.

Q2.

What is meant by capacitance?

Q3.

Why does inserting a dielectric between the plates of a capacitor increase its capacitance?

Q4.

State Ohm's law.

Q5.

What is electrical resistivity?

Q6.

Why does a current-carrying conductor experience a force in a magnetic field?

Q7.

What is magnetic flux?

Q8.

State Faraday's law of electromagnetic induction.

Q9.

State Lenz's law.

Q10.

Why is the magnetic force on a moving charged particle unable to change its speed when the force remains perpendicular to velocity?

SECTION II — PHYSICS NUMERICAL MARATHON

Q11.

A 12V battery is connected to a 6\Omega resistor. Find the current.

Q12.

A 3\Omega resistor carries a current of 4A. Find the power dissipated.

Q13.

A 10\mu F capacitor is charged to 50V. Calculate the charge.

Q14.

Calculate the energy stored in the capacitor in Q13.

Q15.

A wire carrying 5A current has length 0.4m and is perpendicular to a 0.3T magnetic field. Calculate the force.

Q16.

A coil of 200 turns experiences a flux change of 0.01Wb in 0.2s. Find the magnitude of induced emf.

SECTION III — ASSERTION–REASON

Q17.

Assertion: The capacitance of a parallel-plate capacitor increases when the plate area increases.

Reason: Capacitance is proportional to plate area for an ideal parallel-plate capacitor.

Q18.

Assertion: A stationary charged particle in a magnetic field experiences no magnetic force.

Reason: Magnetic force on a charge depends on its velocity.

Q19.

Assertion: The induced current opposes the change in magnetic flux.

Reason: This is the basis of Lenz's law.

SECTION IV — DATA INTERPRETATION

A student obtains the following readings:

2 V

0.4 A

4 V

0.8 A

6 V

1.2 A

8 V

1.6 A

Q20.

Is the relationship approximately linear?

Q21.

Calculate the resistance using the first reading.

Q22.

What happens to current when voltage is doubled?

Q23.

What would be the general shape of the V-I graph?

Q24.

What does the slope of a V-I graph represent?

PHYSICS ANSWERS

Work done per unit charge in moving a test charge between two points.

Charge stored per unit potential difference: [ C=\frac QV ]

The dielectric changes the electric-field relationship and increases capacitance.

[ V=IR ]

Resistance of a material of unit length and unit cross-sectional area.

Interaction between the current and magnetic field produces force.

Measure of magnetic field passing through a surface.

Changing magnetic flux induces emf.

Induced effects oppose the change producing them.

The force is perpendicular to velocity, so it changes direction rather than kinetic-energy magnitude.

[ I=\frac{12}{6}=2A ]

[ P=I^2R=16\times3=48W ]

[ Q=CV ] =10\times10^{-6}\times50 =5\times10^{-4}C 

[ U=\frac12CV^2 ] =0.0125J 

[ F=BIL ] =0.3\times5\times0.4 =0.6N 

[ \varepsilon=N\frac{\Delta\Phi}{\Delta t} ] =200\times\frac{0.01}{0.2} =10V 

Both are correct and the Reason explains the Assertion.

Yes.

[ R=\frac VI=\frac2{0.4}=5\Omega ]

Current doubles.

Approximately a straight line through the origin.

Resistance when V is plotted against I.

PART B — CHEMISTRY MEGA MOCK

SECTION I — CONCEPTS

Q1.

Define electrode potential.

Q2.

What is standard electrode potential?

Q3.

Why is a salt bridge used in an electrochemical cell?

Q4.

Write:

[ E_{cell}=? ]

Q5.

What is conductivity?

Q6.

What is molar conductivity?

Q7.

Define rate of reaction.

Q8.

What is activation energy?

Q9.

What is a catalyst?

Q10.

Define ligand.

SECTION II — NUMERICALS

Q11.

Given:

[ E^\circ_{cathode}=0.80V ]

[ E^\circ_{anode}=0.20V ]

calculate E^\circ_{cell}.

Q12.

A reaction follows first-order kinetics with:

[ k=0.231,min^{-1} ]

Find its half-life.

Q13.

A solution has resistance 25\Omega. Calculate its conductance.

Q14.

Write the relationship between \Delta G^\circ and E^\circ_{cell}.

Q15.

If n=2, F is Faraday's constant and E^\circ_{cell}=0.50V, express \Delta G^\circ.

SECTION III — COORDINATION CHEMISTRY

Q16.

What is coordination number?

Q17.

Differentiate between monodentate and bidentate ligands.

Q18.

Why can coordination compounds show different colours?

Q19.

What is meant by a central metal ion?

Q20.

What is a coordination sphere?

SECTION IV — CASE STUDY

A first-order reaction is investigated experimentally. Its rate constant is determined at two different temperatures.

Q21.

What generally happens to the rate constant when temperature rises?

Q22.

What happens to the half-life if k increases?

Q23.

Why does temperature affect reaction rate?

Q24.

What is the significance of activation energy?

Q25.

How does a catalyst affect the reaction pathway?

CHEMISTRY ANSWERS

Potential associated with an electrode in an electrochemical system.

Electrode potential under standard conditions.

To maintain ionic balance and complete the internal circuit.

[ E_{cell}=E_{cathode}-E_{anode} ]

Ability of a solution to conduct electricity.

Conductivity corresponding to one mole of electrolyte under the defined convention.

Change in concentration of a reactant or product per unit time.

Energy barrier that must be overcome for effective reaction.

A substance that changes reaction rate by providing an alternative pathway.

An electron-pair donor to a central metal atom/ion.

[ E^\circ_{cell}=0.80-0.20=0.60V ]

[ t_{1/2}=\frac{0.693}{0.231}=3,min ]

[ G=\frac1{25}=0.04S ]

[ \Delta G^\circ=-nFE^\circ_{cell} ]

[ \Delta G^\circ=-2F(0.50)=-F ]

Number of donor atoms directly attached to the central metal.

Monodentate has one donor atom; bidentate has two.

Electronic transitions can absorb different wavelengths of visible light.

Metal atom/ion around which ligands are coordinated.

The central metal and its directly attached ligands.

It generally increases.

It decreases.

A greater fraction of molecules can acquire sufficient energy to cross the activation barrier.

It measures the energy barrier for reaction.

It provides an alternative pathway, generally with lower activation energy.

PART C — BIOLOGICAL SCIENCE MEGA MOCK

SECTION I — MOLECULAR BIOLOGY

Q1.

What is a nucleotide?

Q2.

What is DNA replication?

Q3.

Why is DNA replication described as semi-conservative?

Q4.

What is transcription?

Q5.

What is translation?

Q6.

What is a codon?

Q7.

What is gene expression?

Q8.

What is mutation?

SECTION II — EVOLUTION

Q9.

Define variation.

Q10.

What is natural selection?

Q11.

Why is heritable variation important?

Q12.

What is adaptation?

Q13.

What evidence can fossils provide?

Q14.

What is meant by homologous structures?

SECTION III — CASE STUDY

A population contains individuals showing variation in a particular characteristic. Environmental conditions change, and individuals possessing a particular heritable characteristic reproduce more successfully.

Q15.

What biological process is illustrated?

Q16.

Why is heritability important?

Q17.

What can happen to the frequency of the advantageous characteristic over generations?

Q18.

Does the environment directly create every useful inherited variation?

Q19.

Why is variation essential to evolutionary change?

SECTION IV — DIAGRAM PRACTICE

Draw and label:

Q20.

DNA double helix.

Q21.

Replication fork.

Q22.

Basic transcription unit.

Q23.

Chromosome.

Q24.

A diagram showing a suitable evolutionary relationship.

Q25.

Structure of a nucleotide.

BIOLOGY ANSWERS

Basic structural unit of nucleic acids.

Copying of DNA before cell division.

Each daughter molecule contains one old strand and one newly formed strand.

Formation of RNA from a DNA template.

Formation of a polypeptide using mRNA information.

Three-nucleotide sequence on mRNA.

Use of genetic information to produce a functional product.

Change in genetic material.

Differences among individuals.

Differential survival/reproduction associated with heritable variation.

It allows characteristics to be passed to future generations.

A characteristic that helps survival or reproduction in a particular environment.

Evidence concerning past organisms and evolutionary history.

Structures with common evolutionary origin.

Natural selection.

Without heritability, advantageous characteristics would not reliably pass to descendants.

Its frequency may increase.

Evolutionary change generally acts on existing heritable variation; the environment selects rather than simply directing every specific mutation.

It supplies differences upon which selection can act.

PART D — MATHEMATICS MEGA MOCK

CALCULUS

Q1.

Differentiate:

[ y=x^4-2x^3+5x ]

Q2.

Find:

[ \int(4x^3-6x^2+5),dx ]

Q3.

Evaluate:

[ \int_0^1 3x^2dx ]

Q4.

Find:

[ \frac{d}{dx}(\ln x) ]

Q5.

Find the stationary point of:

[ y=x^2-4x+7 ]

DIFFERENTIAL EQUATIONS

Q6.

Solve:

[ \frac{dy}{dx}=6x ]

Q7.

Find the order of:

[ \frac{d^3y}{dx^3}+2\frac{dy}{dx}+y=0 ]

Q8.

Find the degree of:

[ \left(\frac{d^2y}{dx^2}\right)^4+y=0 ]

VECTORS

Q9.

Find the magnitude of:

[ 3\hat i+4\hat j+12\hat k ]

Q10.

Calculate:

[ (\hat i+2\hat j)\cdot(2\hat i-\hat j) ]

Q11.

What is the angle between perpendicular vectors?

Q12.

What is the magnitude of a unit vector?

PROBABILITY

Q13.

A fair die is thrown once. Find the probability of obtaining a number greater than 3.

Q14.

Two coins are tossed. Find the probability of obtaining two tails.

Q15.

If:

[ P(A)=0.35 ]

find:

[ P(A') ]

THREE-DIMENSIONAL GEOMETRY

Q16.

Write the equation of the xz-plane.

Q17.

Write the coordinates of a general point on the y-axis.

Q18.

State the condition for direction cosines.

Q19.

What are direction ratios?

Q20.

Find the distance between:

[ (1,2,3) ]

and

[ (4,6,3) ]

MATHEMATICS ANSWERS

[ 4x^3-6x^2+5 ]

[ x^4-2x^3+5x+C ]

[ 1 ]

[ \frac1x ]

[ x=2,\quad y=3 ]

[ y=3x^2+C ]

[ \sqrt{9+16+144}=13 ]

[ 2-2=0 ]

90^\circ

[ \frac36=\frac12 ]

[ \frac14 ]

[ 0.65 ]

[ y=0 ]

[ (0,y,0) ]

[ l^2+m^2+n^2=1 ]

Ratios proportional to the components of a vector in the specified direction.

[ \sqrt{(4-1)^2+(6-2)^2+(3-3)^2} ] =\sqrt{9+16}=5 

PART E — ENGLISH MEGA WRITING MOCK

SECTION I — READING

Read the passage:

Education is not limited to memorising information. It develops the ability to question, understand, analyse and communicate. A student who learns to think independently can use knowledge in unfamiliar situations. Therefore, meaningful education combines knowledge with reasoning, curiosity and responsible action.

Questions

What is education not limited to?

What abilities does meaningful education develop?

Why is independent thinking valuable?

What should education combine with knowledge?

Give a suitable title.

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