Q. In a galvanic cell, the anode is where:
A.
Reduction occurs
B.
Oxidation occurs
C.
Electrons are gained
D.
The salt bridge is located
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Solution
In a galvanic cell, oxidation occurs at the anode.
Correct Answer:
B
— Oxidation occurs
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Q. In a galvanic cell, which electrode undergoes reduction?
A.
Anode
B.
Cathode
C.
Salt bridge
D.
Electrolyte
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Solution
In a galvanic cell, reduction occurs at the cathode.
Correct Answer:
B
— Cathode
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Q. In a reaction A → B, if the concentration of A decreases from 0.5 M to 0.1 M in 20 minutes, what is the average rate of reaction?
A.
0.02 M/min
B.
0.04 M/min
C.
0.05 M/min
D.
0.06 M/min
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Solution
Average rate = (change in concentration) / (time) = (0.5 - 0.1) / 20 = 0.02 M/min.
Correct Answer:
B
— 0.04 M/min
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Q. In a reaction A → B, if the rate of formation of B is 0.1 mol/L·s, what is the rate of disappearance of A?
A.
0.1 mol/L·s
B.
0.05 mol/L·s
C.
0.2 mol/L·s
D.
0.1 L/mol·s
Show solution
Solution
For the reaction A → B, the rate of disappearance of A is equal to the rate of formation of B, hence it is 0.1 mol/L·s. However, if stoichiometry is considered as 1:1, the rate of disappearance of A is also 0.1 mol/L·s.
Correct Answer:
C
— 0.2 mol/L·s
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Q. In a reaction A → B, if the rate of formation of B is 0.5 mol/L·s, what is the rate of disappearance of A?
A.
0.5 mol/L·s
B.
1.0 mol/L·s
C.
0.25 mol/L·s
D.
0.75 mol/L·s
Show solution
Solution
For the reaction A → B, the rate of disappearance of A is equal to the rate of formation of B, thus it is 1.0 mol/L·s.
Correct Answer:
B
— 1.0 mol/L·s
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Q. In a reaction A → B, if the rate of reaction doubles when the concentration of A is doubled, what is the order of the reaction with respect to A?
A.
Zero order
B.
First order
C.
Second order
D.
Third order
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Solution
If the rate doubles when the concentration of A is doubled, the reaction is first order with respect to A.
Correct Answer:
B
— First order
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Q. In a reaction at equilibrium, if the concentration of a reactant is decreased, what will happen?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Increase the rate of reaction
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Solution
According to Le Chatelier's principle, decreasing the concentration of a reactant will shift the equilibrium to the left to produce more reactants.
Correct Answer:
B
— Shift to the left
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Q. In a reaction at equilibrium, if the concentration of products increases, what will happen to the equilibrium position?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on temperature
Show solution
Solution
According to Le Chatelier's principle, if the concentration of products increases, the equilibrium will shift to the left.
Correct Answer:
A
— Shift to the left
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Q. In a reaction at equilibrium, if the concentration of products is decreased, what will happen?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the temperature
Show solution
Solution
Decreasing the concentration of products will shift the equilibrium to the right to produce more products, according to Le Chatelier's principle.
Correct Answer:
A
— Shift to the right
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Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the equilibrium?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Equilibrium constant increases
Show solution
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium to the right to form more products.
Correct Answer:
A
— Shift to the right
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Q. In a reaction at equilibrium, if the concentration of reactants is increased, what will happen to the equilibrium position?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the reaction
Show solution
Solution
According to Le Chatelier's principle, increasing the concentration of reactants will shift the equilibrium position to the right to produce more products.
Correct Answer:
A
— Shift to the right
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Q. In a reaction at equilibrium, if the temperature is decreased, what will happen to the equilibrium position if the reaction is exothermic?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on the concentration
Show solution
Solution
For an exothermic reaction, decreasing the temperature shifts the equilibrium to the right, favoring the formation of products.
Correct Answer:
A
— Shift to the right
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Q. In a reaction at equilibrium, if the temperature is increased and the reaction is exothermic, what will happen to the equilibrium position?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Equilibrium constant increases
Show solution
Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium position to the left, favoring the reactants.
Correct Answer:
B
— Shift to the left
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Q. In a reaction at equilibrium, if the temperature is increased, what will happen to the equilibrium constant Kc for an endothermic reaction?
A.
Increase
B.
Decrease
C.
No change
D.
Depends on concentration
Show solution
Solution
For an endothermic reaction, increasing temperature shifts the equilibrium to the right, increasing Kc.
Correct Answer:
A
— Increase
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Q. In a reaction mechanism, the slowest step is known as the:
A.
Rate-determining step
B.
Intermediate step
C.
Fast step
D.
Catalytic step
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Solution
The slowest step in a reaction mechanism is called the rate-determining step, as it controls the overall reaction rate.
Correct Answer:
A
— Rate-determining step
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Q. In a reaction mechanism, the slowest step is known as what?
A.
Rate-determining step
B.
Intermediate step
C.
Fast step
D.
Catalytic step
Show solution
Solution
The slowest step in a reaction mechanism is known as the rate-determining step.
Correct Answer:
A
— Rate-determining step
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Q. In a reaction where 2 moles of hydrogen react with 1 mole of oxygen, how many moles of water are produced?
A.
1 mole
B.
2 moles
C.
3 moles
D.
4 moles
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Solution
According to the balanced equation 2H2 + O2 → 2H2O, 2 moles of H2 produce 2 moles of H2O.
Correct Answer:
B
— 2 moles
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Q. In a reaction where ΔH is negative and ΔS is positive, what can be said about ΔG?
A.
ΔG is always negative.
B.
ΔG is always positive.
C.
ΔG is zero.
D.
ΔG depends on temperature.
Show solution
Solution
If ΔH is negative and ΔS is positive, ΔG will always be negative at all temperatures.
Correct Answer:
A
— ΔG is always negative.
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Q. In a reaction where ΔH is positive and ΔS is negative, what is the sign of ΔG at high temperatures?
A.
Positive
B.
Negative
C.
Zero
D.
Cannot be determined
Show solution
Solution
At high temperatures, ΔG will be positive because the positive ΔH and negative ΔS will dominate the equation ΔG = ΔH - TΔS.
Correct Answer:
A
— Positive
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Q. In a reaction, 3 moles of A react with 2 moles of B to produce 4 moles of C. What is the mole ratio of A to C?
A.
3:4
B.
2:3
C.
4:3
D.
1:1
Show solution
Solution
The mole ratio of A to C is 3:4 based on the coefficients in the balanced equation.
Correct Answer:
A
— 3:4
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Q. In a reaction, if the enthalpy change (ΔH) is -100 kJ and the entropy change (ΔS) is 200 J/K, what is the Gibbs free energy change (ΔG) at 298 K?
A.
-100 kJ
B.
-50 kJ
C.
0 kJ
D.
50 kJ
Show solution
Solution
ΔG = ΔH - TΔS = -100 kJ - (298 K * 0.2 kJ/K) = -100 kJ - 59.6 kJ = -159.6 kJ.
Correct Answer:
A
— -100 kJ
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Q. In a reaction, if the rate constant doubles when the temperature increases by 10°C, what is the activation energy (Ea) approximately?
A.
20 kJ/mol
B.
40 kJ/mol
C.
60 kJ/mol
D.
80 kJ/mol
Show solution
Solution
Using the Arrhenius equation, Ea can be estimated to be around 40 kJ/mol.
Correct Answer:
B
— 40 kJ/mol
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Q. In a redox reaction, which species is reduced?
A.
Oxidizing agent
B.
Reducing agent
C.
Product
D.
Reactant
Show solution
Solution
The oxidizing agent is the species that gains electrons and is reduced.
Correct Answer:
A
— Oxidizing agent
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Q. In a reversible process, the change in entropy of the universe is:
A.
Positive
B.
Negative
C.
Zero
D.
Undefined
Show solution
Solution
In a reversible process, the change in entropy of the universe is zero, as the system and surroundings are in equilibrium.
Correct Answer:
C
— Zero
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Q. In a reversible process, the change in Gibbs free energy (ΔG) is:
A.
Always positive
B.
Always negative
C.
Zero at equilibrium
D.
None of the above
Show solution
Solution
In a reversible process, the change in Gibbs free energy (ΔG) is zero at equilibrium.
Correct Answer:
C
— Zero at equilibrium
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Q. In a reversible process, the change in Gibbs free energy is equal to:
A.
Zero
B.
Enthalpy
C.
Entropy
D.
Temperature
Show solution
Solution
In a reversible process at equilibrium, the change in Gibbs free energy is zero.
Correct Answer:
A
— Zero
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Q. In a solution of 0.1 M NH4Cl, what is the pH if the Kb of NH3 is 1.8 x 10^-5?
A.
4.75
B.
5.75
C.
6.75
D.
7.75
Show solution
Solution
Using the formula for weak bases, pH = 14 - pKb = 14 - (14 - 4.75) = 5.75.
Correct Answer:
B
— 5.75
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Q. In a solution of 1 mol of solute in 9 mol of solvent, what is the mole fraction of the solute?
A.
0.1
B.
0.2
C.
0.5
D.
0.9
Show solution
Solution
Mole fraction of solute = moles of solute / (moles of solute + moles of solvent) = 1 / (1 + 9) = 0.1.
Correct Answer:
A
— 0.1
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Q. In a solution of 1 mole of solute B in 3 moles of solvent A, what is the mole fraction of solvent A?
A.
0.25
B.
0.75
C.
0.33
D.
0.67
Show solution
Solution
Mole fraction of A = moles of A / (moles of A + moles of B) = 3 / (3 + 1) = 0.75.
Correct Answer:
B
— 0.75
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Q. In a solution of a non-volatile solute, how does the addition of solute affect the boiling point of the solvent?
A.
It decreases the boiling point
B.
It has no effect on the boiling point
C.
It increases the boiling point
D.
It depends on the nature of the solute
Show solution
Solution
The addition of a non-volatile solute raises the boiling point of the solvent, a phenomenon known as boiling point elevation.
Correct Answer:
C
— It increases the boiling point
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Chemistry Syllabus (JEE Main) MCQ & Objective Questions
The Chemistry Syllabus for JEE Main is crucial for students aiming to excel in their exams. Understanding this syllabus not only helps in grasping fundamental concepts but also enhances performance in objective questions and MCQs. Regular practice with these types of questions is essential for scoring better and mastering important topics.
What You Will Practise Here
Basic Concepts of Chemistry
Atomic Structure and Chemical Bonding
States of Matter: Gases and Liquids
Thermodynamics and Thermochemistry
Equilibrium: Chemical and Ionic
Redox Reactions and Electrochemistry
Hydrocarbons and Environmental Chemistry
Exam Relevance
The Chemistry syllabus is a significant part of CBSE, State Boards, NEET, and JEE exams. Questions from this syllabus often appear in various formats, including multiple-choice questions, assertion-reason type questions, and numerical problems. Familiarity with the common question patterns can greatly enhance your exam preparation and confidence.
Common Mistakes Students Make
Misunderstanding the periodic trends and their implications.
Confusing different types of chemical bonds and their properties.
Neglecting to balance redox reactions properly.
Overlooking the significance of units in thermodynamic calculations.
Failing to apply concepts of equilibrium in problem-solving.
FAQs
Question: What are the key topics I should focus on in the Chemistry syllabus for JEE Main?Answer: Focus on atomic structure, chemical bonding, thermodynamics, and equilibrium as they are frequently tested.
Question: How can I improve my performance in Chemistry MCQs?Answer: Regular practice with past papers and understanding concepts deeply will help you tackle MCQs effectively.
Start your journey towards mastering the Chemistry Syllabus (JEE Main) by solving practice MCQs today. Test your understanding and build confidence for your exams!
