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
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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 which of the following cases does the mesomeric effect dominate over the inductive effect?
A.
Aromatic compounds
B.
Aliphatic compounds
C.
Alkynes
D.
Alkenes
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Solution
In aromatic compounds, the mesomeric effect dominates due to resonance stabilization.
Correct Answer:
A
— Aromatic compounds
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Q. In which of the following compounds does the central atom exhibit dsp3 hybridization?
A.
PCl5
B.
SF6
C.
XeF4
D.
NH3
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Solution
In PCl5, phosphorus exhibits dsp3 hybridization, forming five P-Cl bonds.
Correct Answer:
A
— PCl5
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Q. In which of the following compounds does the central atom exhibit sp hybridization?
A.
C2H4
B.
N2
C.
HCl
D.
C2H2
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Solution
In C2H2, the carbon atoms are sp hybridized, forming a triple bond between them.
Correct Answer:
D
— C2H2
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Q. In which of the following compounds does the central atom have an incomplete octet?
A.
BF3
B.
CH4
C.
H2O
D.
NH3
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Solution
Boron trifluoride (BF3) has an incomplete octet as boron only has six electrons in its valence shell.
Correct Answer:
A
— BF3
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Q. In which of the following compounds does the central atom have sp3d hybridization?
A.
PCl5
B.
SiCl4
C.
XeF4
D.
NH4Cl
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Solution
In PCl5, the phosphorus atom is sp3d hybridized, allowing it to form five P-Cl bonds.
Correct Answer:
A
— PCl5
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Q. In which of the following compounds does the inductive effect play a significant role?
A.
Benzene
B.
Acetic acid
C.
Cyclohexane
D.
Ethylene
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Solution
In acetic acid, the inductive effect of the –COOH group influences the acidity of the compound.
Correct Answer:
B
— Acetic acid
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Q. In which of the following compounds is the bond order equal to 1?
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Solution
H2 has a bond order of 1, indicating a single bond between the two hydrogen atoms.
Correct Answer:
C
— H2
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Q. In which of the following conditions does a gas deviate most from ideal behavior?
A.
High temperature and low pressure
B.
Low temperature and high pressure
C.
High temperature and high pressure
D.
Low temperature and low pressure
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Solution
A gas deviates most from ideal behavior at low temperatures and high pressures due to increased intermolecular forces.
Correct Answer:
B
— Low temperature and high pressure
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Q. In which of the following molecules does the molecular orbital configuration lead to paramagnetism?
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Solution
O2 is paramagnetic due to the presence of two unpaired electrons in its molecular orbitals.
Correct Answer:
B
— O2
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Q. In which of the following molecules does the molecular orbital configuration show unpaired electrons?
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Solution
O2 has two unpaired electrons in its π* orbitals, making it paramagnetic.
Correct Answer:
B
— O2
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Q. In which of the following molecules does the molecular orbital diagram show a paramagnetic behavior?
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Solution
O2 is paramagnetic due to the presence of two unpaired electrons in its molecular orbitals.
Correct Answer:
B
— O2
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Q. In which of the following molecules does the molecular orbital theory predict a paramagnetic behavior?
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Solution
O2 is paramagnetic due to the presence of two unpaired electrons in its molecular orbitals.
Correct Answer:
B
— O2
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Q. In which of the following molecules does the molecular orbital theory predict a triple bond?
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Solution
N2 has a triple bond, with a bond order of 3 according to molecular orbital theory.
Correct Answer:
A
— N2
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Q. In which of the following orbitals would an electron have the highest energy?
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Solution
The 3s orbital has the highest principal quantum number (n=3), indicating it has the highest energy.
Correct Answer:
D
— 3s
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Q. In which of the following reactions is the enthalpy change likely to be the largest?
A.
Dissolving salt in water
B.
Combustion of gasoline
C.
Melting of ice
D.
Sublimation of dry ice
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Solution
The combustion of gasoline releases a large amount of energy, resulting in a large enthalpy change.
Correct Answer:
B
— Combustion of gasoline
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Q. In which of the following reactions is the entropy change expected to be negative?
A.
N2(g) + 3H2(g) → 2NH3(g)
B.
C(s) + O2(g) → CO2(g)
C.
2H2(g) + O2(g) → 2H2O(g)
D.
CaCO3(s) → CaO(s) + CO2(g)
Show solution
Solution
The reaction N2(g) + 3H2(g) → 2NH3(g) results in a decrease in the number of gas molecules, leading to a negative change in entropy.
Correct Answer:
A
— N2(g) + 3H2(g) → 2NH3(g)
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Q. In which of the following scenarios does a liquid exhibit the highest boiling point?
A.
High molecular weight and strong intermolecular forces
B.
Low molecular weight and weak intermolecular forces
C.
High molecular weight and weak intermolecular forces
D.
Low molecular weight and strong intermolecular forces
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Solution
A liquid with high molecular weight and strong intermolecular forces will have a higher boiling point.
Correct Answer:
A
— High molecular weight and strong intermolecular forces
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Q. In which of the following scenarios does a liquid exhibit the highest density?
A.
At its boiling point
B.
At its freezing point
C.
At room temperature
D.
At its critical point
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Solution
A liquid typically exhibits the highest density at room temperature, as it is not at the extremes of phase change.
Correct Answer:
D
— At its critical point
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Q. In which of the following scenarios is the entropy of the system likely to decrease?
A.
Ice melting
B.
Water freezing
C.
Gas expanding
D.
Liquid evaporating
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Solution
The entropy of the system decreases when water freezes, as the molecules become more ordered in the solid state.
Correct Answer:
B
— Water freezing
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Q. In which of the following scenarios is ΔG equal to ΔH?
A.
At high temperatures with ΔS = 0.
B.
At low temperatures with ΔS = 0.
C.
At constant pressure and temperature.
D.
In a phase transition.
Show solution
Solution
During a phase transition, such as melting or boiling, ΔG equals ΔH because the system is at equilibrium.
Correct Answer:
D
— In a phase transition.
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Q. In which of the following scenarios would the entropy of the system decrease?
A.
Ice melting
B.
Water evaporating
C.
Gas compressing
D.
Sugar dissolving in water
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Solution
When a gas is compressed, the number of microstates decreases, leading to a decrease in entropy.
Correct Answer:
C
— Gas compressing
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Q. In which of the following scenarios would you expect a liquid to have the highest viscosity?
A.
At high temperatures
B.
At low temperatures
C.
When mixed with gases
D.
When agitated
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Solution
Viscosity generally decreases with increasing temperature, so a liquid would have the highest viscosity at low temperatures.
Correct Answer:
B
— At low temperatures
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Q. In which of the following species does the molecular orbital configuration show a paramagnetic behavior?
Show solution
Solution
O2 has unpaired electrons in its molecular orbital configuration, making it paramagnetic.
Correct Answer:
B
— O2
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Q. In which of the following states does a liquid exhibit the highest density?
A.
At low temperatures
B.
At high temperatures
C.
At critical temperature
D.
At boiling point
Show solution
Solution
Liquids generally exhibit the highest density at low temperatures.
Correct Answer:
A
— At low temperatures
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Q. In which of the following states of matter do particles have the least freedom of movement?
A.
Solid
B.
Liquid
C.
Gas
D.
Plasma
Show solution
Solution
In solids, particles are closely packed and have limited movement.
Correct Answer:
A
— Solid
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Q. In which process does the entropy of the system decrease?
A.
Freezing of water
B.
Evaporation of water
C.
Sublimation of dry ice
D.
Dissolving salt in water
Show solution
Solution
The freezing of water results in a decrease in the entropy of the system as it transitions from liquid to solid.
Correct Answer:
A
— Freezing of water
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Q. In which scenario would the Gibbs Free Energy of a system be at its minimum?
A.
At equilibrium
B.
At the start of a reaction
C.
At maximum temperature
D.
At maximum pressure
Show solution
Solution
The Gibbs Free Energy of a system is at its minimum at equilibrium, indicating stability.
Correct Answer:
A
— At equilibrium
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Q. In which scenario would ΔG = 0?
A.
At the start of a reaction.
B.
At equilibrium.
C.
When the reaction is spontaneous.
D.
When the reaction is non-spontaneous.
Show solution
Solution
ΔG = 0 occurs at equilibrium, where the forward and reverse reactions occur at the same rate.
Correct Answer:
B
— At equilibrium.
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Q. In which scenario would ΔG be equal to ΔH?
A.
At absolute zero.
B.
When ΔS = 0.
C.
For a spontaneous reaction.
D.
For an endothermic reaction.
Show solution
Solution
ΔG equals ΔH when the entropy change (ΔS) is zero, indicating no change in disorder.
Correct Answer:
B
— When ΔS = 0.
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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!
