JEE Main MCQ & Objective Questions
The JEE Main exam is a crucial step for students aspiring to enter prestigious engineering colleges in India. It tests not only knowledge but also the ability to apply concepts effectively. Practicing MCQs and objective questions is essential for scoring better, as it helps in familiarizing students with the exam pattern and enhances their problem-solving skills. Engaging with practice questions allows students to identify important questions and strengthen their exam preparation.
What You Will Practise Here
Fundamental concepts of Physics, Chemistry, and Mathematics
Key formulas and their applications in problem-solving
Important definitions and theories relevant to JEE Main
Diagrams and graphical representations for better understanding
Numerical problems and their step-by-step solutions
Previous years' JEE Main questions for real exam experience
Time management strategies while solving MCQs
Exam Relevance
The topics covered in JEE Main are not only significant for the JEE exam but also appear in various CBSE and State Board examinations. Many concepts are shared with the NEET syllabus, making them relevant across multiple competitive exams. Common question patterns include conceptual applications, numerical problems, and theoretical questions that assess a student's understanding of core subjects.
Common Mistakes Students Make
Misinterpreting the question stem, leading to incorrect answers
Neglecting units in numerical problems, which can change the outcome
Overlooking negative marking and not managing time effectively
Relying too heavily on rote memorization instead of understanding concepts
Failing to review and analyze mistakes from practice tests
FAQs
Question: How can I improve my speed in solving JEE Main MCQ questions?Answer: Regular practice with timed quizzes and focusing on shortcuts can significantly enhance your speed.
Question: Are the JEE Main objective questions similar to previous years' papers?Answer: Yes, many questions are based on previous years' patterns, so practicing them can be beneficial.
Question: What is the best way to approach JEE Main practice questions?Answer: Start with understanding the concepts, then attempt practice questions, and finally review your answers to learn from mistakes.
Now is the time to take charge of your preparation! Dive into solving JEE Main MCQs and practice questions to test your understanding and boost your confidence for the exam.
Q. In the reaction 4Fe + 3O2 → 2Fe2O3, how many grams of Fe2O3 can be produced from 8 grams of Fe?
A.
16 g
B.
32 g
C.
48 g
D.
24 g
Show solution
Solution
8 g of Fe = 0.143 moles. 4 moles of Fe produce 2 moles of Fe2O3, so 0.0715 moles of Fe2O3 = 0.0715 * 160 g = 11.44 g.
Correct Answer:
C
— 48 g
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, how many moles of Fe are required to react with 6 moles of O2?
A.
4 moles
B.
6 moles
C.
8 moles
D.
12 moles
Show solution
Solution
From the balanced equation, 3 moles of O2 react with 4 moles of Fe. Therefore, 6 moles of O2 will require (4/3) * 6 = 8 moles of Fe.
Correct Answer:
C
— 8 moles
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, how many moles of Fe2O3 are produced from 12 moles of Fe?
A.
2 moles
B.
3 moles
C.
4 moles
D.
6 moles
Show solution
Solution
From the balanced equation, 4 moles of Fe produce 2 moles of Fe2O3. Therefore, 12 moles of Fe will produce (12/4) x 2 = 6 moles of Fe2O3.
Correct Answer:
C
— 4 moles
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, how many moles of Fe2O3 can be produced from 12 moles of Fe?
A.
3 moles
B.
6 moles
C.
9 moles
D.
12 moles
Show solution
Solution
From the stoichiometry, 4 moles of Fe produce 2 moles of Fe2O3. Therefore, 12 moles of Fe will produce (12/4) x 2 = 6 moles of Fe2O3.
Correct Answer:
B
— 6 moles
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, how many moles of Fe2O3 can be produced from 8 moles of Fe?
A.
2 moles
B.
4 moles
C.
6 moles
D.
8 moles
Show solution
Solution
From the balanced equation, 4 moles of Fe produce 2 moles of Fe2O3. Therefore, 8 moles of Fe will produce 4 moles of Fe2O3.
Correct Answer:
B
— 4 moles
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, what is the oxidation state of iron in Fe2O3?
Show solution
Solution
In Fe2O3, iron has an oxidation state of +3.
Correct Answer:
B
— +3
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), if the pressure is increased, which direction will the equilibrium shift?
A.
To the left
B.
To the right
C.
No shift
D.
Depends on temperature
Show solution
Solution
Increasing pressure shifts the equilibrium towards the side with fewer moles of gas, which is the right side in this case.
Correct Answer:
B
— To the right
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), if the temperature is decreased, what will happen to the equilibrium?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in pressure
Show solution
Solution
Decreasing the temperature for an exothermic reaction will shift the equilibrium to the right, favoring the formation of CH3OH.
Correct Answer:
A
— Shift to the right
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what will happen if H2 is removed from the system at equilibrium?
A.
Equilibrium shifts to the right
B.
Equilibrium shifts to the left
C.
No change
D.
Equilibrium constant increases
Show solution
Solution
Removing H2 will shift the equilibrium to the left to produce more H2, thus favoring the reactants.
Correct Answer:
B
— Equilibrium shifts to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what will happen if H2 is removed from the system?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Increase the rate of reaction
Show solution
Solution
Removing H2 will shift the equilibrium to the left to produce more H2, according to Le Chatelier's principle.
Correct Answer:
A
— Shift to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what will happen if H2 is removed?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Equilibrium constant increases
Show solution
Solution
Removing H2 will shift the equilibrium to the left to produce more H2, according to Le Chatelier's principle.
Correct Answer:
B
— Shift to the left
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Q. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what will happen if the volume of the container is decreased?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
Show solution
Solution
Decreasing the volume increases the pressure, which shifts the equilibrium to the side with fewer moles of gas, favoring the production of CH3OH.
Correct Answer:
A
— Shift to the right
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Q. In the reaction Zn + CuSO4 → ZnSO4 + Cu, which element is oxidized?
A.
Zn
B.
Cu
C.
SO4
D.
None of the above
Show solution
Solution
Zinc (Zn) is oxidized as it loses electrons to form Zn2+.
Correct Answer:
A
— Zn
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Q. In the reaction: 2A(g) ⇌ B(g) + C(g), if the volume of the container is decreased, what will happen?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on the temperature
Show solution
Solution
Decreasing the volume increases the pressure, and the equilibrium will shift towards the side with fewer moles of gas, which is the left side in this case.
Correct Answer:
A
— Shift to the left
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Q. In the reaction: 2A(g) ⇌ B(g) + C(g), if the volume of the container is decreased, what will happen to the equilibrium?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on temperature
Show solution
Solution
Decreasing the volume increases the pressure, and the equilibrium will shift to the side with fewer moles of gas, which is the left side in this case.
Correct Answer:
A
— Shift to the left
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Q. In the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens if the temperature is increased?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in Kp
Show solution
Solution
If the reaction is exothermic, increasing the temperature will shift the equilibrium to the left, favoring the reactants.
Correct Answer:
B
— Shift to the left
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Q. In the redox reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is the oxidation state of carbon in CO2?
Show solution
Solution
In CO2, the oxidation state of carbon is +4.
Correct Answer:
C
— +4
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Q. In the van der Waals equation, what do the constants 'a' and 'b' represent?
A.
Pressure and volume
B.
Attraction and volume
C.
Temperature and pressure
D.
Volume and temperature
Show solution
Solution
'a' accounts for the attractive forces between molecules, while 'b' accounts for the volume occupied by the gas molecules.
Correct Answer:
B
— Attraction and volume
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Q. In thermodynamics, what does the first law of thermodynamics state?
A.
Energy cannot be created or destroyed
B.
Entropy always increases
C.
Heat flows from cold to hot
D.
Work done is independent of path
Show solution
Solution
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another.
Correct Answer:
A
— Energy cannot be created or destroyed
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Q. In thermodynamics, what does the first law state?
A.
Energy cannot be created or destroyed
B.
Entropy always increases
C.
Pressure and volume are inversely related
D.
Heat flows from cold to hot
Show solution
Solution
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another.
Correct Answer:
A
— Energy cannot be created or destroyed
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Q. In thermodynamics, what does the term 'enthalpy' refer to?
A.
Internal energy plus pressure times volume
B.
Internal energy minus pressure times volume
C.
Heat content of a system
D.
Work done by a system
Show solution
Solution
Enthalpy is defined as H = U + PV, where U is internal energy, P is pressure, and V is volume.
Correct Answer:
A
— Internal energy plus pressure times volume
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Q. In thin film interference, if the refractive index of the film is greater than that of the surrounding medium, what happens to the phase of the reflected wave?
A.
No phase change
B.
Phase change of π
C.
Phase change of 2π
D.
Phase change of λ
Show solution
Solution
When light reflects off a denser medium, it undergoes a phase change of π (180 degrees).
Correct Answer:
B
— Phase change of π
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Q. In thin film interference, what causes a phase change of π?
A.
Reflection from a denser medium
B.
Reflection from a rarer medium
C.
Transmission through a denser medium
D.
Transmission through a rarer medium
Show solution
Solution
A phase change of π occurs when a wave reflects off a denser medium.
Correct Answer:
A
— Reflection from a denser medium
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Q. In thin film interference, what happens to the colors observed when the thickness of the film increases?
A.
Colors become brighter
B.
Colors change
C.
Colors disappear
D.
Colors remain the same
Show solution
Solution
As the thickness of the film increases, the path difference changes, leading to a change in the observed colors due to interference.
Correct Answer:
B
— Colors change
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Q. In triangle ABC, if a = 7, b = 24, and c = 25, what is the area of the triangle?
A.
84
B.
96
C.
120
D.
144
Show solution
Solution
Using Heron's formula, s = (7 + 24 + 25)/2 = 28. Area = √[s(s-a)(s-b)(s-c)] = √[28(28-7)(28-24)(28-25)] = √[28*21*4*3] = 84.
Correct Answer:
A
— 84
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Q. In triangle ABC, if AB = 10 cm, AC = 6 cm, and angle A = 30°, what is the length of side BC?
A.
8 cm
B.
7 cm
C.
5 cm
D.
4 cm
Show solution
Solution
Using the Law of Cosines: BC² = AB² + AC² - 2 * AB * AC * cos(A) = 10² + 6² - 2 * 10 * 6 * (√3/2) = 100 + 36 - 60√3. BC = √(100 + 36 - 60√3) ≈ 7 cm.
Correct Answer:
B
— 7 cm
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Q. In triangle ABC, if AB = 7 cm, AC = 24 cm, and BC = 25 cm, is triangle ABC a right triangle?
A.
Yes
B.
No
C.
Cannot be determined
D.
Only if angle A is 90°
Show solution
Solution
Using the Pythagorean theorem, 7^2 + 24^2 = 49 + 576 = 625 = 25^2, so triangle ABC is a right triangle.
Correct Answer:
A
— Yes
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Q. In triangle ABC, if AB = 7 cm, AC = 24 cm, and BC = 25 cm, what is the area of the triangle?
A.
84 cm²
B.
96 cm²
C.
120 cm²
D.
140 cm²
Show solution
Solution
Using Heron's formula, the semi-perimeter s = (7 + 24 + 25)/2 = 28. Area = √[s(s-a)(s-b)(s-c)] = √[28(28-7)(28-24)(28-25)] = √[28*21*4*3] = 84 cm².
Correct Answer:
B
— 96 cm²
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Q. In triangle ABC, if AB = 8, AC = 6, and BC = 10, what is the semi-perimeter?
Show solution
Solution
Semi-perimeter s = (AB + AC + BC) / 2 = (8 + 6 + 10) / 2 = 12.
Correct Answer:
B
— 14
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Q. In triangle ABC, if angle A = 45 degrees and angle B = 45 degrees, what is angle C?
A.
45 degrees
B.
60 degrees
C.
90 degrees
D.
135 degrees
Show solution
Solution
The sum of angles in a triangle is 180 degrees. Therefore, angle C = 180 - (45 + 45) = 90 degrees.
Correct Answer:
C
— 90 degrees
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