Stoichiometry-Test-2

intro

Quiz System

Enter time in seconds:

Time left: 30:00

Question 1:

What is the total number of carbon atoms in 34.2g of sucrose (C₁₂H₂₂O₁₁) with molecular weight (M_r) = 342?

A) 6.0 × 10²²
B) 3.6 × 10²⁵
C) 7.2 × 10²³
D) 3.6 × 10²⁴

Topic: Molar Mass and Molecular Weight

Correct Answer: C) 7.2 × 10²³

Detailed Hint:

The question tests the understanding of molar mass and its use in calculating the number of atoms in a given mass of a compound.
Given, molecular weight of sucrose is 342. The number of carbon atoms in one molecule is 12 (C₁₂H₂₂O₁₁).
The total weight of sucrose in the question is 34.2g. To find the total number of sucrose molecules in this mass, we would divide the total weight by the molecular weight of sucrose (number of moles = mass/M_r).
Thus, the number of sucrose molecules in 34.2g = 34.2/342 moles.
Avogadro's number (6 × 10²³) is the number of molecules in one mole. Therefore, the total number of sucrose molecules in 34.2g = (34.2/342) × (6 ×10²³).
Each molecule of sucrose has 12 carbon atoms. Therefore, the total number of carbon atoms = Number of sucrose molecules × 12.
Calculating this gives the total number of carbon atoms as 7.2 × 10²³, hence the correct option is C.

Question 2:

How many isotopes of elements exhibit both even mass numbers and even atomic numbers?

A) 280
B) 300
C) 154
D) 54

Topic: Atomic Structure and Isotopes

Correct Answer: C) 154

Detailed Hint:

The question requires an understanding of isotopes and their classification based on mass numbers and atomic numbers.
Isotopes are variants of a particular element that share the same atomic number but have different mass numbers.
The atomic number of an element is determined by the number of protons, while the mass number is the total number of protons and neutrons in an atom.
In this question, we're looking for isotopes that have both even atomic and mass numbers. The correct answer, as given, is 154, hence option C.

Question 3:

What is the density of oxygen gas under standard temperature and pressure (STP) conditions?

A) 2.1 g/L
B) 7 g/L
C) 1 g/L
D) 1.43 g/L

Topic: Gas Laws and Density

Correct Answer: D) 1.43 g/L

Detailed Hint:

The question requires knowledge of the concept of density, specifically as it applies to gases under standard temperature and pressure (STP) conditions.
Density of a gas at STP is generally calculated using the formula: Molar mass/22.4.
The molar mass of oxygen is 32, hence the density of oxygen at STP = 32/22.4.
Upon calculation, the value comes out to be 1.43 g/L, therefore, the correct option is D.

Question 4:

How many moles of water are contained in a 720g sample?

A) 20
B) 40
C) 60
D) 80

Topic: Mole Concept and Stoichiometry

Correct Answer: B) 40 moles

Detailed Hint:

The question tests your understanding of the mole concept, specifically in relation to mass-mole conversions.
The molecular mass of water (H₂O) is 18g/mol.
To find the number of moles in a given mass of a substance, we divide the mass of the substance by its molecular mass.
Therefore, the number of moles in 720g of water = 720/18.
This calculation gives us 40 moles, hence the correct answer is B.

Question 5:

What is the weight of 6.022×10²⁰ atoms of silver (atomic mass = 108u)?

A) 108×10³ g
B) 108 g
C) 0.108 g
D) 10.8 g

Topic: Atomic Mass and Mole Concept

Correct Answer: C) 0.108 g

Detailed Hint:

The question examines your understanding of atomic mass and the mole concept.
Atomic mass of silver is given as 108u.
1 mole of silver, which is equivalent to 6.023×10²³ atoms, weighs 108g.
Therefore, the weight of 6.023×10²⁰ atoms of silver can be calculated by proportion: (108g / 6.023x10²³ atoms) * 6.022x10²⁰ atoms.
This calculation yields a result of 0.108g, thus the correct answer is C.

Question 6:

What is the definition of a limiting reactant in a chemical reaction?

A) The reactant with more than 1 mole
B) The reactant with less than one mole
C) The reactant that is consumed first
D) The reactant that limits the energy produced by the reaction

Topic: Chemical Reactions and Stoichiometry

Correct Answer: C) The reactant that is consumed first

Detailed Hint:

This question tests your understanding of chemical reactions, specifically the concept of a limiting reactant.
A limiting reactant in a chemical reaction is the substance that gets used up first, therefore determining the maximum amount of product that can be formed.
Regardless of the number of moles present, the reactant which gets fully consumed first is termed the 'limiting reactant'.
Hence, the correct answer is C.

Question 7:

How is one mole defined?

A) A quantity with mass equal to its atomic/molecular mass
B) A quantity with mass equal to half of its atomic/molecular mass
C) One gram of any quantity
D) One kilogram of any quantity

Topic: Mole Concept

Correct Answer: A) A quantity with mass equal to its atomic/molecular mass

Detailed Hint:

This question tests your understanding of the fundamental concept of a mole in chemistry.
'One mole' is defined as an amount of substance that contains as many entities (atoms, molecules, or other particles) as there are atoms in exactly 12 grams of carbon-12.
In simpler terms, one mole of any substance is a quantity that has a mass (in grams) equal to its atomic or molecular mass.
Therefore, the correct answer is A.

Question 8:

Which of the following pairs are iso-electronic (i.e., have equal number of electrons)?

A) Cl and Cl–
B) Na+ and Ne
C) Al+3 and Cl
D) Mg+2 and Ne+1

Topic: Atomic Structure and Iso-electronic Species

Correct Answer: B) Na+ and Ne

Short Hint:

Iso-electronic species are those that have the same number of electrons.
Na+ and Ne both have 10 electrons.
Therefore, the correct answer is B.

Question 9:

How much volume (in liters) of oxygen at standard temperature and pressure (STP) is needed to completely convert 1.5 moles of Sulphur into Sulphur dioxide?

A) 11.2 L
B) 22.4 L
C) 33.6 L
D) 44.8 L

Topic: Chemical Reactions and Gas Laws

Correct Answer: C) 33.6 L

Short Hint:

The balanced chemical equation for the reaction is S + O₂ ⟶ SO₂, which tells us that 1 mole of Sulphur reacts with 1 mole of Oxygen to produce 1 mole of Sulphur dioxide.
At STP, 1 mole of any gas occupies 22.4 L.
Therefore, 1.5 moles of Sulphur would require 1.5 * 22.4 L = 33.6 L of oxygen.

Question 10:

What is the number of electrons present in 1.8 ml of water?

A) 6.02 × 10²³
B) 6.02 × 10²⁴
C) 6.02 × 10²²
D) 6.02 × 10²⁵

Topic: Molecular Structure and Mole Concept

Correct Answer: A) 6.02 × 10²³

Detailed Hint:

Each H₂O molecule, which consists of 2 hydrogen atoms and 1 oxygen atom, has a total of 10 electrons.
1 mole of water weighs 18 grams, so 1.8 grams of water is 0.1 mole.
Applying Avogadro's number, 0.1 moles of water contains 0.1 * 6.02 x 10²³ = 0.6022 x 10²³ molecules of water.
Then, the total number of electrons is 0.6022 x 10²³ molecules * 10 electrons/molecule = 6.02 x 10²³ electrons.

Question 11:

What is the mass ratio of Sulphur to Oxygen in the compound SO₂?

A) 1 : 2
B) 2 : 1
C) 1 : 1
D) 1 : 4

Topic: Stoichiometry and Mole Concept

Correct Answer: C) 1 : 1

Detailed Hint:

This problem is assessing your grasp on stoichiometry and the mole concept.
In SO₂, the mass of Sulphur (S) is 32g and the mass of Oxygen (O₂) is also 32g.
Hence, the ratio of their masses is 32 : 32, which simplifies to 1 : 1.
The correct answer is therefore C.

Question 12:

What is the weight ratio of one mole of carbon to one mole of magnesium?

A) 1 : 1
B) 2 : 1
C) 1 : 2
D) 2 : 3

Topic: Mole Concept and Atomic Weight

Correct Answer: C) 1 : 2

Detailed Hint:

This question is testing your knowledge of the mole concept and atomic weight.
The weight of one mole of carbon is 12, while the weight of one mole of magnesium is 24.
Therefore, the weight ratio of carbon (C) to magnesium (Mg) is 1 : 2.
The correct answer is C.

Question 13:

What type of substance is ice cream?

A) Pure substance
B) Mixture
C) Compound
D) Element

Topic: Matter and Its Classification

Correct Answer: B) Mixture

Short Hint:

Ice cream is a mixture of various ingredients, such as milk, cream, flavoring substances, sugar, dry fruit, and other compounds.
Therefore, it is not a pure substance, compound, or element, but a mixture.

Question 14:

What's the mass of a single molecule of oxygen?

A) 2.656 x 10^-23 gm
B) 5.312 x 10^-23 gm
C) 1.66 x 10²⁴ gm
D) 32 gm

Topic: Atomic Structure and Mole Concept

Correct Answer: B) 5.312 x 10^-23 gm

Short Hint:

An oxygen molecule contains 6.02 x 10²³ molecules in one mole, which weighs 32 gm.
Therefore, the mass of one oxygen molecule is 32 / 6.02 x 10²³ = 5.312 x 10^-23 gm.

Question 15:

Which of these statements regarding isotopes is incorrect?

A) They have different mass numbers.
B) They share the same chemical properties.
C) They have varying physical properties.
D) They occupy different positions on the periodic table.

Topic: Atomic Structure and Periodicity

Correct Answer: D) They occupy different positions on the periodic table.

Detailed Hint:

Isotopes, having the same number of protons, occupy the same position on the periodic table.
Therefore, the assertion that they occupy different positions on the periodic table is incorrect.
Hence, the correct answer is D.

Question 16:

What does 46 gm of nitrogen dioxide at STP contain?

A) 6.022 x 10²³ molecules of the gas
B) 22,400 cm³ of the gas
C) 1 gram atom of gas
D) 1 mole of gas
E) Both A, B, D

Topic: Mole Concept and Gas Laws

Correct Answer: E) Both A, B, D

Detailed Hint:

The number of moles in 46g of NO₂ equals 46 divided by the molar weight of NO₂ (which is 14 + 32), which amounts to one mole of gas.
At STP, one mole of gas occupies 22,400 cm³.
Additionally, according to Avogadro's number, one mole of a substance contains 6.022 x 10²³ units (atoms, molecules, or ions).
Consequently, options A, B, and D are correct.
Hence, the correct answer is E.

Question 17:

What is the most comprehensible way for chemists to express quantities?

A) Utilizing formulas
B) Utilizing symbols
C) Utilizing shapes
D) Utilizing moles

Topic: Mole Concept and Chemical Calculations

Correct Answer: D) Utilizing mo les

Detailed Hint:

Since atoms combine in whole number ratios with each other, all calculations involving their chemical activities become simpler when using Avogadro’s concept of a mole.
Thus, the correct answer is D.

Question 18:

Which of the following concentration terms remains unaffected by changes in temperature?

A) Only molality
B) Both molality and mole fraction
C) Both molality and normality
D) Only molarity

Topic: Molarity, Molality, and Mole Fraction

Correct Answer: B) Both molality and mole fraction

Detailed Hint:

This question is testing your understanding of molarity, molality, and mole fraction.
Of the given options, both molality and mole fraction are not influenced by temperature changes.
Hence, the correct answer is B.

Question 19:

One mole equals the number of atoms found in:

A) 1g of carbon
B) 6g of carbon
C) 12g of carbon
D) 12kg of carbon

Topic: Mole Concept and Avogadro's Number

Correct Answer: C) 12g of carbon

Detailed Hint:

This question is about your understanding of the mole concept and Avogadro's number.
One mole corresponds to the number of atoms contained in 12g of carbon.
Therefore, the correct answer is C.

Question 20:

What is the equivalent of 1 atomic mass unit (amu) in kilograms?

A) 1.6×10^-23 kg
B) 1.6×10^-27 kg
C) 1.6×10^-31 kg
D) 1.6×10^-34 kg

Topic: Atomic Mass Unit

Correct Answer: B) 1.6×10^-27 kg

Detailed Hint:

This question aims to test your understanding of the atomic mass unit and its equivalence in kilograms.
The atomic mass unit (amu) is a standard unit of mass that quantifies mass on an atomic or molecular scale.
1 amu is equivalent to 1.6×10^-27 kg.
Therefore, the correct answer is B.

Question 21:

Which type of ion formation process is always exothermic?

A) Formation of uni-negative ion
B) Formation of uni-positive ion
C) Formation of di-negative ion
D) Formation of di-positive ion

Topic: Ion Formation and Energy

Correct Answer: A) Formation of uni-negative ion

Detailed Hint:

This question is about your understanding of ion formation and its energy implications.
When an electron is added to a neutral atom to form a uni-negative ion, the attraction between the nucleus and the newly added electron is very high, releasing energy and thus making the process exothermic.
Therefore, the correct answer is A.

Question 22:

How many moles of ions are contained in 98g of H₂SO₄?

A) 4.0 moles of ions
B) 1 mole of ion
C) 2 moles of ions
D) 3.0 moles of ions

Topic: Mole Concept and Ion Formation

Correct Answer: D) 3.0 moles of ions

Detailed Hint:

This question is about your knowledge of the mole concept and how it applies to ion formation.
Given the amount of H₂SO₄ is 98g, the number of moles of H₂SO₄ is 98/98 = 1 mole.
Upon dissociation, H₂SO₄ splits up into ions: 2H⁺ and SO₄^2-. For every mole of H₂SO₄, there are 2 moles of H⁺ and 1 mole of SO₄^2-.
Therefore, 1 mole of H₂SO₄ produces 3 moles of ions, and the correct answer is D.

Question 23:

What volume will 28g of N₂ gas occupy at standard temperature and pressure (STP)?

A) 22.41 dm³
B) 44.82 dm³
C) 44.82 cm³
D) 2.241 dm³

Topic: Molar Volume and STP

Correct Answer: A) 22.41 dm³

Detailed Hint:

This question examines your knowledge of molar volume at standard temperature and pressure (STP).
One mole of any gas at STP occupies a volume of 22.4 dm³.
The molar mass of nitrogen gas (N₂) is 28g/mole. Thus, 28g of N₂ gas is equivalent to 1 mole.
Consequently, 28g of N₂ gas will occupy a volume of 22.41 dm³ at STP. Therefore, the correct answer is A.

Question 24:

Choose the correct statement about the yield in a chemical reaction:

A) The actual yield is always less than the theoretical yield.
B) The percentage yield equals the actual yield divided by the theoretical yield times 100.
C) The actual yield is not influenced by experimental errors.
D) The efficiency of a chemical reaction depends solely on the quantity of the product produced.

Topic: Yield and Efficiency in a Chemical Reaction

Correct Answer: B) The percentage yield equals the actual yield divided by the theoretical yield times 100.

Detailed Hint:

This question is about your understanding of the terms yield and efficiency in the context of a chemical reaction.
Both experimental and human errors can impact the actual yield of a chemical reaction.
Therefore, the statement that the actual yield is not influenced by experimental errors is incorrect.
Hence, the correct answer is B.

Question 25:

How many total atoms are found in a 49.0g sample of sulphuric acid (H₂SO₄)?

A) 7 x 3 x 10²³ atoms
B) 7 x 8 x 10²³ atoms
C) 5 x 6 x 10²³ atoms
D) 6 x 6 x 10²³ atoms

Topic: Mole Concept and Atomic Composition

Correct Answer: A) 7 x 3 x 10²³ atoms

Detailed Hint:

This question tests your understanding of the mole concept and atomic composition.
Given that the weight of H₂SO₄ is 49g and its molar mass is 98g/mole, the number of moles of H₂SO₄ is 49/98, which equals 0.5 moles.
Each molecule of H₂SO₄ contains 7 atoms (2 hydrogen, 1 sulfur, and 4 oxygen atoms).
Therefore, the total number of atoms in 49g of H₂SO₄ is 7 x 0.5 x Avogadro's number, which equals 7 x 3.02 x 10²³ atoms. Hence, the correct answer is A.

Question 26:

The equation 2H₂(g) + O₂(g) yields to what?

A) 2H₂(l)
B) 2H₂O(g)
C) 2H₂O(g) + O₂(g)
D) None of the above

Topic: Chemical Reaction Equations

Correct Answer: B) 2H₂O(g)

Detailed Hint:

This question measures your understanding of the balancing of chemical equations.
The reaction given is the classic example of hydrogen combustion where hydrogen gas reacts with oxygen gas to produce water.
The balanced chemical equation for this reaction is 2H₂(g) + O₂(g) → 2H₂O(g).
Thus, the correct answer is B.

Question 27:

Which of the following contain the highest number of molecules?

A) 7g of N₂
B) 2g of H₂
C) 16g of NO₂
D) 16g of O₂

Topic: Mole and Molecule Concept

Correct Answer: B) 2g of H₂

Detailed Hint:

This question is about your comprehension of the mole and molecule concepts.
The quantity of molecules can be calculated by the formula No. of moles = Weight (W) / Molecular weight (M).
Evaluating each option with the above formula shows that 2g of H₂ has the maximum number of moles and therefore the maximum number of molecules.
Hence, the correct answer is B.

Question 28:

How many molecules are there in a 4.4g sample of CO₂ gas?

A) 6.023 x 10²³ molecules
B) 5.023 x 10²³ molecules
C) 6.023 x 10²⁴ molecules
D) 6.023 x 10²² molecules

Topic: Mole and Molecule Concept

Correct Answer: D) 6.023 x 10²² molecules

Detailed Hint:

This question tests your understanding of the concept of moles and molecules.
Given that 1 mole of CO₂ equals 44g and corresponds to Avogadro's number of molecules (6.023 x 10²³ molecules), you can calculate the number of molecules in any other mass of CO₂.
Therefore, in a 4.4g sample of CO₂, there would be (6.023x10²³/44) x 4.4 = 6.023 x 10²² molecules.
Hence, the correct option is D.

Question 29:

What volume does 0.5 moles of a gas occupy at standard temperature and pressure (STP)?

A) 5.6 L
B) 11.2 L
C) 22.4 L
D) 44.8 L

Topic: Gas Laws and Mole Concept

Correct Answer: B) 11.2 L

Detailed Hint:

This question examines your ability to apply the concept of moles in the context of gas laws.
One mole of any gas at STP occupies a volume of 22.4 liters.
Therefore, 0.5 moles of the same gas would occupy half of this volume, i.e., 11.2 liters.
Hence, the correct answer is option B.

Question 30:

If a compound has an empirical formula of C3H4O and a molecular mass of 110.02, what is its molecular formula?

A) C3H3O
B) C6H8O2
C) C9H9O3
D) C3H6O2

Topic: Molecular Mass and Empirical Formula

Correct Answer: B) C6H8O2

Detailed Hint:

This question tests your understanding of molecular and empirical formulas.
The empirical formula mass is 36 + 16 + 3 = 55.
The ratio of the molecular mass to the empirical formula mass is n = 110.02/55 = 2.
Therefore, the molecular formula is n times the empirical formula, i.e., 2 x C3H4O = C6H8O2.
Thus, the correct answer is option B.

Question 31:

How many moles of methane are needed to yield 22g of CO2 (g) upon combustion?

A) 0.5 mol
B) 1 mol
C) 0.25 mol
D) 1.5 mol

Topic: Stoichiometry

Correct Answer: A) 0.5 mol

Detailed Hint:

This question is about your understanding of stoichiometry.
The balanced chemical reaction for the combustion of methane is CH4 + 2O2 → CO2 + 2H2O.
The molar mass of CO2 is 44g/mol. Therefore, 44g of CO2 is produced from the combustion of 16g of CH4.
Hence, 22g of CO2 would be produced from (16/44) x 22 = 8g of CH4.
Thus, the number of moles of CH4 required is 8/16 = 0.5 moles.
Therefore, the correct answer is option A.

Question 32:

Which element among the following has the greatest number of isotopes?

A) Oxygen
B) Carbon
C) Tin
D) Chlorine

Topic: Isotopes

Correct Answer: C) Tin

Detailed Hint:

The question probes your knowledge about isotopes.
Isotopes are variants of a particular chemical element, differing in neutron number.
The number of isotopes varies from element to element, and Tin is known to have a significant number of stable isotopes.
Accordingly, Tin (option C) is the correct answer.

Question 33:

Which of the following possesses the highest mass of hydrogen atoms?

A) 0.5 moles C₂H₂O₄
B) 1.1 moles C₃H₈O₃
C) 1.5 moles C₆H₈O₆
D) 4.0 moles C₃H₈O₃

Topic: Mole Concept

Correct Answer: D) 4.0 moles C₃H₈O₃

Detailed Hint:

This question assesses your understanding of the mole concept and its application to determine the mass of an atom in a compound.
It is necessary to calculate the mass of hydrogen in each option (considering the mole number and the hydrogen content in each compound).
Upon calculation, it can be found that the highest mass of hydrogen atoms is contained in 4.0 moles of C₃H₈O₃. This makes D) the correct answer.

Question 34:

If an organic compound has an empirical formula of CH₂O and a molar mass of 90 grams, what might be its molecular formula? (Ar of C = 12, H = 1.008 and O = 16).

A) C₆H₆O₂
B) C₃H₃O
C) C₉H₉O₃
D) C₃H₆O₃

Topic: Molecular and Empirical Formulas

Correct Answer: D) C₃H₆O₃

Detailed Hint:

This question tests your ability to calculate the molecular formula from the empirical formula and molar mass.
The empirical formula mass of CH₂O equals 30g. The molar mass of the compound is given as 90g.
The ratio between the molar mass and the empirical formula mass, denoted by n, equals 90/30 = 3.
Thus, the molecular formula is n times the empirical formula, which is 3(CH₂O) = C₃H₆O₃.
The correct answer is hence D) C₃H₆O₃.

Question 35:

What is the weight in grams of three moles of a Nitrogen atom?

A) 28g
B) 42g
C) 84g
D) 14g

Topic: Mole Concept

Correct Answer: B) 42g

Detailed Hint:

This question examines your understanding of the mole concept, particularly the concept of molar mass.
The molar mass of Nitrogen (N) is 14g/mol. This means that 1 mole of Nitrogen atoms weighs 14 grams.
We are asked to find the mass of 3 moles of Nitrogen. This can be calculated by multiplying the number of moles by the molar mass of Nitrogen.
Therefore, the weight of 3 moles of Nitrogen is 3 * 14g = 42g.
Hence, the correct answer is option B) 42g.

Stoichiometry-Test-2

Question 1:

Topic: Molar Mass and Molecular Weight

Question 2:

Topic: Atomic Structure and Isotopes

Question 3:

Topic: Gas Laws and Density

Question 4:

Topic: Mole Concept and Stoichiometry

Question 5:

Topic: Atomic Mass and Mole Concept

Question 6:

Topic: Chemical Reactions and Stoichiometry

Question 7:

Topic: Mole Concept

Question 8:

Topic: Atomic Structure and Iso-electronic Species

Question 9:

Topic: Chemical Reactions and Gas Laws

Question 10:

Topic: Molecular Structure and Mole Concept

Question 11:

Topic: Stoichiometry and Mole Concept

Question 12:

Topic: Mole Concept and Atomic Weight

Question 13:

Topic: Matter and Its Classification

Question 14:

Topic: Atomic Structure and Mole Concept

Question 15:

Topic: Atomic Structure and Periodicity

Question 16:

Topic: Mole Concept and Gas Laws

Question 17:

Topic: Mole Concept and Chemical Calculations

Question 18:

Topic: Molarity, Molality, and Mole Fraction

Question 19:

Topic: Mole Concept and Avogadro's Number

Question 20:

Topic: Atomic Mass Unit

Question 21:

Topic: Ion Formation and Energy

Question 22:

Topic: Mole Concept and Ion Formation

Question 23:

Topic: Molar Volume and STP

Question 24:

Topic: Yield and Efficiency in a Chemical Reaction

Question 25:

Topic: Mole Concept and Atomic Composition

Question 26:

Topic: Chemical Reaction Equations

Question 27:

Topic: Mole and Molecule Concept

Question 28:

Topic: Mole and Molecule Concept

Question 29:

Topic: Gas Laws and Mole Concept

Question 30:

Topic: Molecular Mass and Empirical Formula

Question 31:

Topic: Stoichiometry

Question 32:

Topic: Isotopes

Question 33:

Topic: Mole Concept

Question 34:

Topic: Molecular and Empirical Formulas

Question 35:

Topic: Mole Concept

Test Results