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 2Fe + 3Cl2 → 2FeCl3, how many grams of FeCl3 can be produced from 10 g of Fe?
A.
20 g
B.
30 g
C.
40 g
D.
50 g
Show solution
Solution
10 g of Fe = 0.18 moles. 2 moles of Fe produce 2 moles of FeCl3. 0.18 moles of FeCl3 = 0.18 * 162.5 g = 29.25 g.
Correct Answer:
C
— 40 g
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many grams of FeCl3 can be produced from 4 grams of Fe?
A.
12 g
B.
20 g
C.
30 g
D.
40 g
Show solution
Solution
4 g of Fe = 0.071 moles. 0.071 moles of Fe produce 0.071 * 2 = 0.142 moles of FeCl3 = 0.142 * 162.5 g = 23 g.
Correct Answer:
B
— 20 g
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Q. In the reaction 2Fe + 3Cl2 → 2FeCl3, how many moles of Cl2 are needed to react with 4 moles of Fe?
A.
3 moles
B.
6 moles
C.
4 moles
D.
2 moles
Show solution
Solution
According to the stoichiometry, 2 moles of Fe require 3 moles of Cl2. Therefore, 4 moles of Fe will require 6 moles of Cl2.
Correct Answer:
B
— 6 moles
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being oxidized?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
Show solution
Solution
Carbon (C) is being oxidized to carbon dioxide (CO2).
Correct Answer:
B
— C
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being reduced?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
Show solution
Solution
Fe2O3 is being reduced to Fe as it gains electrons.
Correct Answer:
A
— Fe2O3
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, which element is oxidized?
A.
Iron
B.
Carbon
C.
Oxygen
D.
None
Show solution
Solution
Carbon is oxidized as it loses electrons to form CO2.
Correct Answer:
B
— Carbon
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Q. In the reaction 2Fe^3+ + 2I^- → 2Fe^2+ + I2, which species is the reducing agent?
A.
Fe^3+
B.
I^-
C.
Fe^2+
D.
I2
Show solution
Solution
I^- donates electrons to Fe^3+, thus it is the reducing agent.
Correct Answer:
B
— I^-
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of oxygen are required to completely react with 4 grams of hydrogen?
A.
16 g
B.
8 g
C.
32 g
D.
4 g
Show solution
Solution
4 g of H2 = 2 moles. 1 mole of O2 is needed for 2 moles of H2, so 1 mole of O2 = 32 g is required.
Correct Answer:
B
— 8 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of oxygen are required to react with 4 grams of hydrogen?
A.
16 g
B.
8 g
C.
4 g
D.
2 g
Show solution
Solution
First, calculate moles of H2: 4 g / 2 g/mol = 2 moles. From the reaction, 2 moles of H2 require 1 mole of O2. Therefore, 2 moles of O2 = 32 g.
Correct Answer:
B
— 8 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of water are produced from 4 grams of hydrogen?
A.
18 g
B.
36 g
C.
54 g
D.
72 g
Show solution
Solution
4 grams of H2 is 2 moles (4 g / 2 g/mol). According to the equation, 2 moles of H2 produce 2 moles of H2O, which is 36 g (2 moles x 18 g/mol).
Correct Answer:
B
— 36 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many grams of water can be produced from 4 grams of hydrogen?
A.
36 g
B.
18 g
C.
72 g
D.
9 g
Show solution
Solution
4 g of H2 = 2 moles. 2 moles of H2 produce 2 moles of H2O = 2 * 18 g = 36 g.
Correct Answer:
A
— 36 g
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Q. In the reaction 2H2 + O2 → 2H2O, how many liters of H2O vapor are produced from 4 liters of H2?
A.
4 L
B.
8 L
C.
2 L
D.
6 L
Show solution
Solution
4 L of H2 produces 4 L of H2O vapor at STP.
Correct Answer:
B
— 8 L
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Q. In the reaction 2H2 + O2 → 2H2O, how many liters of water vapor are produced from 4 liters of hydrogen at STP?
A.
4 L
B.
8 L
C.
2 L
D.
6 L
Show solution
Solution
4 L of H2 produces 4 L of H2O since the ratio is 1:1.
Correct Answer:
B
— 8 L
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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of O2 are required to completely react with 6 moles of H2?
A.
2 moles
B.
3 moles
C.
4 moles
D.
6 moles
Show solution
Solution
From the balanced equation, 2 moles of H2 require 1 mole of O2. Therefore, 6 moles of H2 will require (6/2) = 3 moles of O2.
Correct Answer:
B
— 3 moles
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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of O2 are required to react with 6 moles of H2?
A.
3 moles
B.
4 moles
C.
6 moles
D.
2 moles
Show solution
Solution
According to the stoichiometry of the reaction, 2 moles of H2 require 1 mole of O2. Therefore, 6 moles of H2 will require (6/2) = 3 moles of O2.
Correct Answer:
A
— 3 moles
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Q. In the reaction 2H2 + O2 → 2H2O, how many moles of water are produced from 4 moles of hydrogen?
A.
2 moles
B.
4 moles
C.
6 moles
D.
8 moles
Show solution
Solution
According to the stoichiometry of the reaction, 2 moles of H2 produce 2 moles of H2O. Therefore, 4 moles of H2 will produce 4 moles of H2O.
Correct Answer:
B
— 4 moles
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Q. In the reaction 2H2 + O2 → 2H2O, if 3 moles of O2 are available, how many moles of H2 are required?
A.
3 moles
B.
6 moles
C.
1.5 moles
D.
4.5 moles
Show solution
Solution
According to the stoichiometry, 1 mole of O2 requires 2 moles of H2. Therefore, 3 moles of O2 will require 3 x 2 = 6 moles of H2.
Correct Answer:
B
— 6 moles
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Q. In the reaction 2H2 + O2 → 2H2O, if you start with 3 moles of O2, how many moles of H2 are required?
A.
3 moles
B.
6 moles
C.
1.5 moles
D.
4 moles
Show solution
Solution
According to the stoichiometry, 1 mole of O2 requires 2 moles of H2. Therefore, 3 moles of O2 will require 6 moles of H2.
Correct Answer:
B
— 6 moles
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Q. In the reaction 2H2 + O2 → 2H2O, what is the ratio of moles of hydrogen to moles of oxygen?
A.
1:1
B.
2:1
C.
2:2
D.
1:2
Show solution
Solution
The balanced equation shows that 2 moles of H2 react with 1 mole of O2, giving a ratio of 2:1.
Correct Answer:
B
— 2:1
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Q. In the reaction 2H2 + O2 → 2H2O, which element is oxidized?
Show solution
Solution
Oxygen (O) is oxidized as it goes from 0 in O2 to -2 in H2O.
Correct Answer:
B
— O
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Q. In the reaction 2Na + Cl2 → 2NaCl, how many grams of NaCl can be produced from 5 g of Na?
A.
10 g
B.
15 g
C.
20 g
D.
25 g
Show solution
Solution
5 g of Na = 0.217 moles. 2 moles of Na produce 2 moles of NaCl, so 0.217 moles of NaCl = 0.217 * 58.5 g = 12.7 g.
Correct Answer:
A
— 10 g
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens if SO2 is removed from the system?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase in temperature
Show solution
Solution
Removing SO2 will shift the equilibrium to the left to produce more SO2, according to Le Chatelier's principle.
Correct Answer:
B
— Shift to the left
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what happens to the equilibrium if the volume of the container is decreased?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase the rate of reaction
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 right side (2 moles of SO3).
Correct Answer:
A
— Shift to the right
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what is the effect of increasing the pressure on the equilibrium?
A.
Shift to the left
B.
Shift to the right
C.
No effect
D.
Depends on the temperature
Show solution
Solution
Increasing the pressure will shift the equilibrium towards the side with fewer moles of gas, which is the right side in this case (2 moles of SO3).
Correct Answer:
B
— Shift to the right
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what is the effect of increasing the concentration of SO2?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the rate of reaction
Show solution
Solution
Increasing the concentration of a reactant shifts the equilibrium position to the right, favoring the formation of products (SO3).
Correct Answer:
A
— Shifts to the right
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Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if SO3 is removed from the system?
A.
Equilibrium shifts to the left
B.
Equilibrium shifts to the right
C.
No change
D.
Equilibrium constant increases
Show solution
Solution
Removing SO3 will shift the equilibrium to the right to produce more SO3, according to Le Chatelier's principle.
Correct Answer:
B
— Equilibrium shifts to the right
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Q. In the reaction 3A + 2B → 4C, if 6 moles of A are used, how many moles of C will be produced?
A.
4 moles
B.
6 moles
C.
8 moles
D.
12 moles
Show solution
Solution
From the stoichiometry, 3 moles of A produce 4 moles of C. Therefore, 6 moles of A will produce (6 moles A) x (4 moles C / 3 moles A) = 8 moles of C.
Correct Answer:
C
— 8 moles
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Q. In the reaction 3H2 + N2 → 2NH3, how many moles of nitrogen are required to produce 6 moles of ammonia?
A.
3 moles
B.
2 moles
C.
1 mole
D.
4 moles
Show solution
Solution
According to the stoichiometry, 2 moles of NH3 require 1 mole of N2. Therefore, 6 moles of NH3 will require 3 moles of N2.
Correct Answer:
A
— 3 moles
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Q. In the reaction 3H2 + N2 → 2NH3, which element is oxidized?
Show solution
Solution
Hydrogen (H) is oxidized as it goes from an oxidation state of 0 to +1 in NH3.
Correct Answer:
A
— H
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Q. In the reaction 4Al + 3O2 → 2Al2O3, how many moles of Al2O3 are produced from 12 moles of Al?
A.
2 moles
B.
3 moles
C.
6 moles
D.
8 moles
Show solution
Solution
According to the stoichiometry, 4 moles of Al produce 2 moles of Al2O3. Therefore, 12 moles of Al will produce (12/4) x 2 = 6 moles of Al2O3.
Correct Answer:
C
— 6 moles
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