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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.

Chemistry Syllabus (JEE Main) Mathematics Syllabus (JEE Main) Physics Syllabus (JEE Main)

Q. What is the speed of a wave on a string if the tension is 100 N and the mass per unit length is 2 kg/m?

A. 5 m/s
B. 10 m/s
C. 15 m/s
D. 20 m/s

Solution

The speed of a wave on a string is given by the formula v = sqrt(T/μ), where T is the tension and μ is the mass per unit length. Here, v = sqrt(100/2) = sqrt(50) = 10 m/s.

Correct Answer: B — 10 m/s

Q. What is the speed of a wave on a string if the tension is 100 N and the mass per unit length is 0.5 kg/m?

A. 20 m/s
B. 10 m/s
C. 5 m/s
D. 15 m/s

Solution

The speed v of a wave on a string is given by v = √(T/μ), where T is the tension and μ is the mass per unit length. Here, v = √(100/0.5) = √200 = 10 m/s.

Correct Answer: A — 20 m/s

Q. What is the speed of light in a medium with a refractive index of 1.5?

A. 2 x 10^8 m/s
B. 3 x 10^8 m/s
C. 1.5 x 10^8 m/s
D. 1 x 10^8 m/s

Solution

The speed of light in a medium is given by c/n. Therefore, speed = 3 x 10^8 / 1.5 = 2 x 10^8 m/s.

Correct Answer: A — 2 x 10^8 m/s

Q. What is the speed of light in a vacuum?

A. 3 x 10^8 m/s
B. 3 x 10^6 m/s
C. 3 x 10^5 m/s
D. 3 x 10^7 m/s

Solution

The speed of light in a vacuum is approximately 3 x 10^8 m/s.

Correct Answer: A — 3 x 10^8 m/s

Q. What is the speed of sound in air at 20°C?

A. 343 m/s
B. 330 m/s
C. 300 m/s
D. 350 m/s

Solution

The speed of sound in air at 20°C is approximately 343 m/s.

Correct Answer: A — 343 m/s

Q. What is the speed of sound in air at room temperature (20°C)?

A. 343 m/s
B. 300 m/s
C. 1500 m/s
D. 1200 m/s

Solution

The speed of sound in air at 20°C is approximately 343 m/s.

Correct Answer: A — 343 m/s

Q. What is the spin quantum number (m_s) for an electron in an orbital?

A. 0
B. +1/2
C. -1/2
D. 1

Solution

The spin quantum number can be +1/2 or -1/2 for an electron in an orbital.

Correct Answer: B — +1/2

Q. What is the spin quantum number (m_s) for an electron with a clockwise spin?

A. -1/2
B. 0
C. +1/2
D. 1

Solution

The spin quantum number (m_s) is +1/2 for an electron with clockwise spin.

Correct Answer: C — +1/2

Q. What is the spin quantum number (m_s) for an electron?

A. 0
B. +1/2
C. -1/2
D. Both +1/2 and -1/2

Solution

The spin quantum number (m_s) can be +1/2 or -1/2 for an electron.

Correct Answer: D — Both +1/2 and -1/2

Q. What is the standard acceleration due to gravity in m/s²?

A. 9.8
B. 10
C. 9.81
D. 9.75

Solution

The standard acceleration due to gravity is approximately 9.81 m/s².

Correct Answer: C — 9.81

Q. What is the standard deviation of the data set {10, 12, 23, 23, 16, 23, 21, 16}?

A. 5
B. 6
C. 4
D. 3

Solution

Mean = 19.5, Variance = 25, Standard Deviation = √25 = 5.

Correct Answer: A — 5

Q. What is the standard deviation of the data set {10, 12, 23, 23, 16, 23, 21}?

A. 5.5
B. 4.5
C. 6.5
D. 3.5

Solution

Mean = 19.14, Variance = 20.25, Standard Deviation = √20.25 = 4.5.

Correct Answer: B — 4.5

Q. What is the standard deviation of the data set {4, 8, 6, 5, 3}?

A. 1.58
B. 2.58
C. 3.58
D. 4.58

Solution

Mean = 5.2. Variance = [(4-5.2)² + (8-5.2)² + (6-5.2)² + (5-5.2)² + (3-5.2)²]/5 = 6.56. Standard Deviation = √6.56 ≈ 2.56.

Correct Answer: B — 2.58

Q. What is the standard deviation of the data set: 1, 2, 3, 4, 5?

A. 1
B. 1.5
C. 2
D. 2.5

Solution

Mean = 3. Standard Deviation = sqrt[((1-3)^2 + (2-3)^2 + (3-3)^2 + (4-3)^2 + (5-3)^2)/5] = sqrt[2] = 1.414.

Correct Answer: A — 1

Q. What is the standard electrode potential of the hydrogen electrode?

A. 0.00 V
B. 0.34 V
C. 1.23 V
D. 0.76 V

Solution

The standard electrode potential of the hydrogen electrode is defined as 0.00 V.

Correct Answer: A — 0.00 V

Q. What is the standard enthalpy change for the formation of a compound?

A. ΔHf
B. ΔHc
C. ΔHrxn
D. ΔHsol

Solution

The standard enthalpy change for the formation of a compound is denoted as ΔHf.

Correct Answer: A — ΔHf

Q. What is the standard enthalpy change for the formation of an element in its standard state?

A. Zero
B. Positive
C. Negative
D. Depends on the element

Solution

The standard enthalpy change for the formation of an element in its standard state is defined as zero.

Correct Answer: A — Zero

Q. What is the standard enthalpy change for the formation of water from its elements?

A. -285.83 kJ/mol
B. -241.82 kJ/mol
C. -393.5 kJ/mol
D. -572.4 kJ/mol

Solution

The standard enthalpy change for the formation of water (H2 + 1/2 O2 -> H2O) is -285.83 kJ/mol.

Correct Answer: A — -285.83 kJ/mol

Q. What is the standard enthalpy change for the reaction 2H2 + O2 → 2H2O if the enthalpy of formation of H2O is -285.8 kJ/mol?

A. -571.6 kJ
B. -285.8 kJ
C. 0 kJ
D. 285.8 kJ

Solution

ΔH = 2 * (-285.8 kJ) = -571.6 kJ

Correct Answer: A — -571.6 kJ

Q. What is the standard enthalpy change for the reaction 2H2(g) + O2(g) → 2H2O(l)?

A. -285.83 kJ/mol
B. -241.82 kJ/mol
C. -572.4 kJ/mol
D. -1000 kJ/mol

Solution

The standard enthalpy of formation of water is -241.82 kJ/mol.

Correct Answer: B — -241.82 kJ/mol

Q. What is the standard enthalpy change for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g) if ΔHf°(NH3) = -45.9 kJ/mol?

A. -91.8 kJ
B. 0 kJ
C. 45.9 kJ
D. 91.8 kJ

Solution

ΔH = 2 * ΔHf°(NH3) = 2 * (-45.9) = -91.8 kJ

Correct Answer: A — -91.8 kJ

Q. What is the standard enthalpy change for the reaction: C(s) + O2(g) → CO2(g) if ΔHf° for CO2 is -393.5 kJ/mol?

A. -393.5 kJ
B. 0 kJ
C. 393.5 kJ
D. None of the above

Solution

The standard enthalpy change is equal to the enthalpy of formation of CO2, which is -393.5 kJ.

Correct Answer: A — -393.5 kJ

Q. What is the standard enthalpy change of formation for a substance?

A. The enthalpy change when one mole of a compound is formed from its elements in their standard states.
B. The enthalpy change when one mole of a substance is completely burned in oxygen.
C. The enthalpy change when one mole of a substance is dissolved in water.
D. The enthalpy change when one mole of a gas is compressed to a smaller volume.

Solution

The standard enthalpy change of formation is defined as the enthalpy change when one mole of a compound is formed from its elements in their standard states.

Correct Answer: A — The enthalpy change when one mole of a compound is formed from its elements in their standard states.

Q. What is the standard enthalpy change of formation for an element in its standard state?

A. 0 kJ/mol
B. 100 kJ/mol
C. 298 kJ/mol
D. 1 kJ/mol

Solution

The standard enthalpy change of formation for an element in its standard state is defined as 0 kJ/mol.

Correct Answer: A — 0 kJ/mol

Q. What is the standard enthalpy change of formation for elements in their standard state?

A. 0 kJ/mol
B. 100 kJ/mol
C. 298 kJ/mol
D. 1 kJ/mol

Solution

The standard enthalpy change of formation for elements in their standard state is defined as zero.

Correct Answer: A — 0 kJ/mol

Q. What is the standard enthalpy change of formation for water (H2O) at 25°C?

A. -285.83 kJ/mol
B. -241.82 kJ/mol
C. -393.5 kJ/mol
D. -241.0 kJ/mol

Solution

The standard enthalpy change of formation for water at 25°C is -241.82 kJ/mol.

Correct Answer: B — -241.82 kJ/mol

Q. What is the standard enthalpy of formation for an element in its standard state?

A. 0 kJ/mol
B. 100 kJ/mol
C. 298 kJ/mol
D. 1 kJ/mol

Solution

The standard enthalpy of formation for an element in its standard state is defined as 0 kJ/mol.

Correct Answer: A — 0 kJ/mol

Q. What is the standard enthalpy of formation for elements in their standard state?

A. 0 kJ/mol
B. 1 kJ/mol
C. 100 kJ/mol
D. Not defined

Solution

The standard enthalpy of formation for elements in their standard state is defined as 0 kJ/mol.

Correct Answer: A — 0 kJ/mol

Q. What is the standard entropy change (ΔS°) for the reaction: 2 SO2(g) + O2(g) → 2 SO3(g)?

A. Positive
B. Negative
C. Zero
D. Cannot be determined

Solution

The reaction decreases the number of gas molecules from 3 to 2, leading to a decrease in disorder and thus a negative ΔS°.

Correct Answer: B — Negative

Q. What is the standard entropy change (ΔS°) for the reaction: 2H2(g) + O2(g) → 2H2O(g)?

A. Positive
B. Negative
C. Zero
D. Cannot be determined

Solution

The reaction results in a decrease in the number of gas molecules (from 3 to 2), leading to a negative change in entropy.

Correct Answer: B — Negative

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