Mole Concept: Essential Study for Competitive Exams

Mole Concept

Q. What is the mass of 0.75 moles of sulfuric acid (H2SO4)?

A. 75 g
B. 98 g
C. 147 g
D. 50 g

Solution

Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = moles x molar mass = 0.75 moles x 98 g/mol = 73.5 g.

Correct Answer: B — 98 g

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Q. What is the mass of 2 moles of sulfuric acid (H2SO4)?

A. 98 g
B. 196 g
C. 294 g
D. 392 g

Solution

Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = 2 moles x 98 g/mol = 196 g.

Correct Answer: B — 196 g

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Q. What is the mass of 3 moles of NaCl?

A. 87 g
B. 58.5 g
C. 174 g
D. 3 g

Solution

Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol. Mass = moles x molar mass = 3 moles x 58.5 g/mol = 174 g.

Correct Answer: C — 174 g

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Q. What is the mass of 3 moles of sulfuric acid (H2SO4)?

A. 98 g
B. 196 g
C. 294 g
D. 392 g

Solution

Molar mass of H2SO4 = 2*1 + 32 + 4*16 = 98 g/mol. Mass = 3 moles x 98 g/mol = 294 g.

Correct Answer: B — 196 g

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Q. What is the molar mass of CaCO3?

A. 100 g/mol
B. 120 g/mol
C. 80 g/mol
D. 60 g/mol

Solution

Molar mass of CaCO3 = 40 + 12 + 16*3 = 100 g/mol.

Correct Answer: A — 100 g/mol

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Q. What is the molar mass of sulfuric acid (H2SO4)?

A. 98 g/mol
B. 96 g/mol
C. 100 g/mol
D. 92 g/mol

Solution

Molar mass = 2*1 + 32 + 4*16 = 98 g/mol.

Correct Answer: A — 98 g/mol

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Q. What is the number of atoms in 2 moles of aluminum (Al)? (2044)

A. 6.022 x 10^23
B. 1.2044 x 10^24
C. 3.011 x 10^23
D. 12.044 x 10^24

Solution

Number of atoms = moles x Avogadro's number = 2 moles x 6.022 x 10^23 atoms/mole = 1.2044 x 10^24 atoms.

Correct Answer: B — 1.2044 x 10^24

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Q. What is the number of atoms in 2 moles of CaCO3?

A. 6.022 x 10^23
B. 1.2044 x 10^24
C. 3.011 x 10^23
D. 1.8066 x 10^24

Solution

Each CaCO3 has 5 atoms (1 Ca, 1 C, 3 O). Number of atoms = moles x atoms per molecule x Avogadro's number = 2 moles x 5 x 6.022 x 10^23 = 1.206 x 10^24 atoms.

Correct Answer: D — 1.8066 x 10^24

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Q. What is the number of atoms in 2 moles of Na2SO4?

A. 6.022 x 10^23
B. 1.2044 x 10^24
C. 1.2044 x 10^25
D. 3.011 x 10^23

Solution

Na2SO4 has 2 Na + 1 S + 4 O = 7 atoms. Number of atoms = moles x atoms per mole = 2 moles x 7 atoms = 14 atoms = 1.2044 x 10^24 atoms.

Correct Answer: B — 1.2044 x 10^24

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Q. What is the number of atoms in 2 moles of NaCl? (2044)

A. 6.022 x 10^23
B. 1.2044 x 10^24
C. 1.2044 x 10^25
D. 3.011 x 10^23

Solution

Each NaCl unit has 2 atoms (Na and Cl). Therefore, 2 moles of NaCl contain 2 x 6.022 x 10^23 x 2 = 1.2044 x 10^24 atoms.

Correct Answer: B — 1.2044 x 10^24

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Q. What is the number of moles in 10 grams of Na?

A. 0.43
B. 0.22
C. 0.5
D. 0.1

Solution

Molar mass of Na = 23 g/mol. Number of moles = mass / molar mass = 10 g / 23 g/mol = 0.43 moles.

Correct Answer: A — 0.43

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Q. What is the number of moles in 10 grams of NaOH?

A. 0.25
B. 0.5
C. 0.75
D. 1

Solution

Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 10 g / 40 g/mol = 0.25 moles.

Correct Answer: B — 0.5

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Q. What is the number of moles in 100 grams of NaOH?

A. 1
B. 2
C. 0.5
D. 0.25

Solution

Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 100 g / 40 g/mol = 2.5 moles.

Correct Answer: A — 1

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Q. What is the number of moles in 180 grams of glucose (C6H12O6)?

A. 1
B. 2
C. 0.5
D. 3

Solution

Molar mass of C6H12O6 = 6*12 + 12*1 + 6*16 = 180 g/mol. Number of moles = mass/molar mass = 180 g / 180 g/mol = 1 mole.

Correct Answer: A — 1

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Q. What is the number of moles in 44 grams of CO2?

A. 1
B. 2
C. 0.5
D. 0.25

Solution

Molar mass of CO2 = 12 + 16*2 = 44 g/mol. Number of moles = mass/molar mass = 44 g / 44 g/mol = 1 mole.

Correct Answer: A — 1

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Q. What is the number of moles in 5 liters of a 2 M NaCl solution?

A. 2.5
B. 5
C. 10
D. 1

Solution

Moles = Molarity x Volume = 2 moles/L x 5 L = 10 moles.

Correct Answer: A — 2.5

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Q. What is the volume occupied by 1 mole of an ideal gas at STP?

A. 22.4 L
B. 24 L
C. 20 L
D. 18 L

Solution

At STP, 1 mole of an ideal gas occupies 22.4 liters.

Correct Answer: A — 22.4 L

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Q. What is the volume occupied by 4 moles of an ideal gas at STP?

A. 22.4 L
B. 44.8 L
C. 67.2 L
D. 89.6 L

Solution

At STP, 1 mole of gas occupies 22.4 L. Therefore, 4 moles occupy 4 x 22.4 L = 89.6 L.

Correct Answer: B — 44.8 L

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Q. What is the volume of 1 mole of an ideal gas at STP?

A. 22.4 L
B. 24 L
C. 10 L
D. 1 L

Solution

At STP (Standard Temperature and Pressure), 1 mole of an ideal gas occupies 22.4 liters.

Correct Answer: A — 22.4 L

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Q. What is the volume of 4 moles of an ideal gas at STP?

A. 22.4 L
B. 44.8 L
C. 89.6 L
D. 112 L

Solution

Volume = moles x volume per mole = 4 moles x 22.4 L/mole = 89.6 L.

Correct Answer: C — 89.6 L

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Mole Concept MCQ & Objective Questions

The Mole Concept is a fundamental topic in chemistry that plays a crucial role in various examinations. Understanding this concept not only helps in grasping the basics of chemical calculations but also enhances problem-solving skills. Practicing MCQs and objective questions related to the Mole Concept is essential for students aiming to score better in their exams. By tackling these practice questions, you can identify important questions and strengthen your exam preparation.

What You Will Practise Here

Definition and significance of a mole in chemistry
Conversions between moles, mass, and number of particles
Avogadro's Law and its applications
Calculating molar mass and its importance
Stoichiometry and its relation to the Mole Concept
Limiting reactants and yield calculations
Real-life applications of the Mole Concept in various chemical reactions

Exam Relevance

The Mole Concept is a vital part of the syllabus for CBSE, State Boards, NEET, and JEE. Questions related to this topic often appear in various formats, including numerical problems, theoretical questions, and conceptual MCQs. Students can expect to encounter questions that require them to calculate moles, apply stoichiometric principles, and interpret chemical equations. Familiarity with common question patterns will greatly enhance your confidence during exams.

Common Mistakes Students Make

Confusing moles with mass and volume, leading to incorrect conversions
Overlooking the significance of Avogadro's number in calculations
Misunderstanding stoichiometric ratios in chemical reactions
Failing to identify limiting reactants in problems
Neglecting to practice unit conversions, which can lead to errors in answers

FAQs

Question: What is a mole in chemistry?
Answer: A mole is a unit that measures the amount of substance, defined as containing exactly 6.022 x 10²³ particles, such as atoms or molecules.

Question: How do I calculate the molar mass of a compound?
Answer: To calculate the molar mass, sum the atomic masses of all the atoms in the compound's formula, expressed in grams per mole.

Now is the time to sharpen your skills! Dive into our practice MCQs on the Mole Concept and test your understanding. By solving these important Mole Concept questions for exams, you will be well-prepared to tackle any challenge that comes your way. Start practicing today!

Mole Concept

Mole Concept MCQ & Objective Questions

What You Will Practise Here

Exam Relevance

Common Mistakes Students Make

FAQs

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