1.
A chemical can be defined as
Correct Answer
C. Any substance that has a definite composition
Explanation
The correct answer is "any substance that has a definite composition." This definition accurately describes a chemical because chemicals are substances that are made up of specific elements and compounds in fixed proportions. This definition encompasses all types of chemicals, whether they are natural or synthetic, toxic or non-toxic, and whether they are used in food or not. It emphasizes the importance of the composition of a substance in determining whether it can be classified as a chemical.
2.
Inorganice chemistry is the study of
Correct Answer
A. Non-carbon related compounds
Explanation
Inorganic chemistry is the study of non-carbon related compounds. This branch of chemistry focuses on the properties, structures, and reactions of elements and compounds that do not contain carbon. It explores the behavior of metals, minerals, and nonmetals, as well as their interactions with each other and other substances. Inorganic chemistry plays a crucial role in various fields such as materials science, medicine, environmental science, and industry. By studying non-carbon compounds, scientists can gain a deeper understanding of their properties and potential applications.
3.
Organic chemistry is the study of
Correct Answer
D. Carbon-containing compounds
Explanation
Organic chemistry is the study of carbon-containing compounds. This branch of chemistry focuses on the structure, properties, composition, reactions, and synthesis of organic molecules. Carbon is unique because it can form stable bonds with other carbon atoms and a wide range of other elements, allowing for the creation of countless organic compounds. By studying organic chemistry, scientists can understand and manipulate the behavior of these compounds, which are essential to life and have numerous applications in fields such as medicine, agriculture, and materials science.
4.
Which of the following is an extensive property of matter?
Correct Answer
C. Volume
Explanation
Volume is an extensive property of matter because it depends on the amount of substance present. It is a measure of the space occupied by a substance and can be changed by adding or removing more of the substance. In contrast, intensive properties like melting point and boiling point do not depend on the amount of substance and remain constant regardless of the quantity. Density, although it is a measure of mass per unit volume, is also an intensive property because it does not change with the amount of substance.
5.
Which of the following is an intensive property of matter?
Correct Answer
B. Density
Explanation
Density is an intensive property of matter because it is a characteristic that does not depend on the amount of substance present. It is defined as the mass per unit volume of a substance. Regardless of the size or amount of the substance, its density remains the same. On the other hand, amount of energy, volume, and mass are extensive properties, as they depend on the size or amount of the substance.
6.
The two most important properties of all matter are
Correct Answer
B. Taking up space and having mass
Explanation
The correct answer is taking up space and having mass. These two properties are fundamental to all matter. "Taking up space" refers to the fact that matter occupies a certain volume or physical space. "Having mass" refers to the amount of matter present in an object. These properties are universal and apply to all forms of matter, whether it is a solid, liquid, or gas.
7.
A measure of the quantity of matter is
Correct Answer
D. Mass
Explanation
Mass is a measure of the quantity of matter in an object. It represents the amount of material present in an object, regardless of its location or the force acting on it. Mass is a fundamental property of matter and is commonly measured in units such as kilograms or grams. Density refers to the mass per unit volume, weight is the force of gravity acting on an object, and volume is the amount of space occupied by an object. While these factors can be related to mass, they are not direct measures of the quantity of matter.
8.
Under ordinary conditions of temperature and pressure, the particles in a gas are
Correct Answer
B. Very far from one another
Explanation
The particles in a gas are very far from one another because gases have low density and their particles are in constant random motion, resulting in large spaces between them. This allows gases to easily expand and fill the entire volume of a container.
9.
Plasma is the fourth state of matter. In the Plasma state...
Correct Answer
B. Atoms lose electrons.
Explanation
In the plasma state, atoms lose electrons. This is because plasma is a highly ionized gas, meaning that it contains an abundance of free electrons and positively charged ions. The high energy in plasma causes atoms to lose their outermost electrons, resulting in the formation of ions. Therefore, atoms losing electrons is a characteristic of the plasma state of matter.
10.
If a mixture is uniform in a composition, it is said to be
Correct Answer
A. Homogeneous
Explanation
A mixture that is uniform in composition is called homogeneous. This means that all the components of the mixture are evenly distributed throughout, resulting in a consistent appearance and properties throughout the mixture. In a homogeneous mixture, the different substances are not chemically bonded to each other, but rather they are physically mixed together. This is in contrast to a compound, which is a substance formed by the chemical bonding of two or more elements.
11.
A homogeneous mixture is also called
Correct Answer
C. A solution
Explanation
A homogeneous mixture is also called a solution because it is a uniform mixture where the components are evenly distributed at a molecular level. In a solution, the solute (substance being dissolved) is dispersed in the solvent (substance doing the dissolving) to form a single phase. This term is commonly used in chemistry to describe a mixture that appears the same throughout and has the same properties in all its parts.
12.
If a mixture is not unifom throughout, it is called
Correct Answer
B. Heterogeneous
Explanation
A mixture that is not uniform throughout is called heterogeneous. In a heterogeneous mixture, the different substances are not evenly distributed and can be easily distinguished. This is in contrast to a homogeneous mixture, where the substances are evenly distributed and cannot be easily distinguished. The term "chemically bonded" refers to a different concept, where atoms are joined together in a chemical reaction. A solution is a type of homogeneous mixture where one substance is dissolved in another.
13.
The unit m^3 measures
Correct Answer
C. Volume
Explanation
The unit m^3 is used to measure volume. Volume refers to the amount of space occupied by an object or substance. It is a three-dimensional measurement that considers the length, width, and height of an object or the capacity of a container. Therefore, the correct answer is volume.
14.
Which of these statements about density is true?
Correct Answer
C. Density is a pHysical property
Explanation
Density is a physical property because it is a characteristic of a substance that can be measured and compared without changing the substance itself. It is defined as the mass of a substance per unit volume. Physical properties, such as density, can be used to identify and classify substances.
15.
The density of pure diamond is 3.5 g/cm^3. What is the volume of a diamond with a mass of 0.25 g?
Correct Answer
A. 0.071cm^3
Explanation
The density of a substance is defined as its mass per unit volume. In this question, we are given the mass of the diamond (0.25 g) and the density of pure diamond (3.5 g/cm^3). To find the volume, we can use the formula: density = mass/volume. Rearranging the formula, we get volume = mass/density. Plugging in the values, we get volume = 0.25 g / 3.5 g/cm^3 = 0.071 cm^3. Therefore, the correct answer is 0.071 cm^3.
16.
A measurement that closely agrees with an accepted value is best described as
Correct Answer
D. Accurate
Explanation
An accurate measurement is one that closely agrees with an accepted value, indicating that it is close to the true value. Accuracy is a measure of how correct or exact a measurement is. Precise refers to the consistency or repeatability of a measurement, while reproducible implies that the measurement can be replicated by others. Significant refers to the importance or relevance of a measurement. In this context, the best description for a measurement that closely agrees with an accepted value would be accurate.
17.
A numerical result is said to have good precision if
Correct Answer
B. Repeated measurements agree closely.
Explanation
The correct answer is "repeated measurements agree closely". This is because precision refers to the consistency and reproducibility of measurements. If repeated measurements of the same quantity yield similar results, it indicates good precision. This suggests that the measurement process is reliable and the uncertainty associated with the measurements is small.
18.
The measurement 0.035550 g rounded of to two significant figures would be
Correct Answer
C. 0.036 g
Explanation
When rounding to two significant figures, the rule is to look at the digit to the right of the second significant figure. If it is 5 or greater, the second significant figure is increased by 1. In this case, the third significant figure is 5, so the second significant figure (3) is increased by 1, resulting in 0.04 g. However, since we are rounding to two significant figures, the final answer is 0.036 g.
19.
Which of these measurements has only nonsignificant zeros?
Correct Answer
A. 0.0037 mL
Explanation
The measurement 0.0037 mL has only nonsignificant zeros because the zeros before the decimal point are considered placeholders and do not add any value to the measurement. Therefore, they are not significant. The zeros in the other measurements (60.0 mL, 400. mL, 506 mL) are either between significant digits or after a decimal point, making them significant zeros.
20.
How is the measurement 0.000065 cm written in scientific notation?
Correct Answer
B. 6.5 X 10^-5 cm
Explanation
The given measurement, 0.000065 cm, can be written in scientific notation as 6.5 x 10^-5 cm. In scientific notation, the number is written as a decimal between 1 and 10, multiplied by a power of 10. In this case, the decimal is 6.5, and the power of 10 is -5, indicating that the decimal point needs to be moved 5 places to the left to convert the number to standard form.
21.
When 1.92 X 10^-6 kg is divided by 6.8 X 10^2 mL, the quotient equals
Correct Answer
D. 2.8 X 10^-9 kg/mL
Explanation
The given question involves dividing 1.92 X 10^-6 kg by 6.8 X 10^2 mL. To divide the numbers in scientific notation, we subtract the exponents and divide the coefficients. In this case, the coefficient 1.92 is divided by 6.8, resulting in 0.2823529412. The exponents are subtracted, giving us 10^-6 divided by 10^2, which is equal to 10^-8. Therefore, the quotient is 0.2823529412 X 10^-8 kg/mL, which can be simplified to 2.8 X 10^-9 kg/mL.
22.
Dalton incorporated the law of conservation of mass into his atomic theory by asserting that
Correct Answer
A. Atoms are indivisible
Explanation
Dalton incorporated the law of conservation of mass into his atomic theory by asserting that atoms are indivisible. This means that atoms cannot be further divided into smaller particles. By recognizing the indivisibility of atoms, Dalton was able to explain how the total mass of substances remains constant during chemical reactions, in accordance with the law of conservation of mass.
23.
If two or more compounds are composed of the same two elements, the ratio of the masses of one element that combine with a fixed mass of the other element is a simple whole number. This is a statement of the law
Correct Answer
C. Multiple proportions
Explanation
The statement that if two or more compounds are composed of the same two elements, the ratio of the masses of one element that combine with a fixed mass of the other element is a simple whole number is a statement of the law of multiple proportions. This law states that when two elements combine to form different compounds, the ratio of their masses will always be in simple whole numbers. This observation supports the idea that elements combine in fixed ratios to form compounds, and helps to explain the composition and properties of different compounds.
24.
Which of the following statements is true according to modern atomic theory?
Correct Answer
A. Atoms of the same element may have different masses
Explanation
According to modern atomic theory, atoms of the same element may have different masses due to the presence of isotopes. Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different masses. This discovery was made through experiments such as mass spectrometry, which allowed scientists to identify and measure the different isotopes of an element based on their masses. Therefore, it is true that atoms of the same element may have different masses.
25.
Experiments with cathode rays led to the discovery of the
Correct Answer
D. Electron
Explanation
Experiments with cathode rays led to the discovery of the electron. Cathode rays are streams of electrons that were observed in vacuum tubes during the late 19th century. These experiments provided evidence for the existence of negatively charged particles, which were later named electrons. This discovery revolutionized our understanding of atomic structure and led to the development of the electron as a fundamental particle in the field of physics.
26.
Whose series of experiments identified the nucleus of the atom?
Correct Answer
A. Rutherford
Explanation
Rutherford's series of experiments identified the nucleus of the atom. Through his famous gold foil experiment, Rutherford discovered that the atom has a small, dense, and positively charged nucleus at its center. This groundbreaking discovery revolutionized the understanding of atomic structure and laid the foundation for the development of modern atomic theory. Rutherford's experiments provided evidence for the existence of the nucleus and disproved the previous model proposed by J.J. Thomson, known as the "plum pudding" model.
27.
A nuclear particle that has about the same mass a proton, but with no electrical charge, is called a(n)
Correct Answer
B. Neutron
Explanation
A nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a neutron. Neutrons are found in the nucleus of an atom and are responsible for holding the nucleus together. They have a mass of approximately 1 atomic mass unit and are electrically neutral, meaning they do not have any positive or negative charge. Neutrons play a crucial role in nuclear reactions and are commonly used in nuclear power plants and research facilities.
28.
Isotopes are atoms of the same element that have different
Correct Answer
B. Masses
Explanation
Isotopes are atoms of the same element that have different masses. This is because isotopes have the same number of protons and electrons, which determines the element they belong to, but they have different numbers of neutrons. Neutrons contribute to the mass of an atom, so isotopes of the same element have different masses. Therefore, the correct answer is "masses".
29.
As the mass number of an element's isotopes of an element increases, the number of protons
Correct Answer
C. Remains the same
Explanation
The mass number of an element's isotopes refers to the total number of protons and neutrons in the nucleus of an atom. Since the number of protons in an atom determines its atomic number and therefore its identity as a specific element, the number of protons remains the same regardless of the mass number. Therefore, as the mass number of an element's isotopes increases, the number of protons remains the same.
30.
The relative atomic mass of an atom can be found by comparing the mass of the atom to the mass of
Correct Answer
A. One-atom of carbon-12
Explanation
The relative atomic mass of an atom can be found by comparing its mass to the mass of one atom of carbon-12. This is because carbon-12 is used as the standard reference for atomic masses. The atomic mass of carbon-12 is defined as exactly 12 atomic mass units, so comparing the mass of other atoms to carbon-12 allows us to determine their relative atomic masses.
31.
The average atomic mass of an element is the average of the atomic masses of its
Correct Answer
A. Naturally occurring isotopes
Explanation
The average atomic mass of an element is calculated by taking into account the masses of all its naturally occurring isotopes. Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei. Naturally occurring isotopes are those that are found in nature and are stable. The average atomic mass is determined by multiplying the mass of each isotope by its relative abundance and then summing these values. This provides a weighted average that represents the typical atomic mass of the element.
32.
The mass of 2.0 mol of oxygen atoms (atomic mass 16.00 amu) is
Correct Answer
B. 32 g
Explanation
The atomic mass of oxygen is 16.00 amu. Since there are 2.0 moles of oxygen atoms, we can calculate the mass by multiplying the atomic mass by the number of moles. Therefore, the mass of 2.0 mol of oxygen atoms is 2.0 mol * 16.00 amu/mol = 32 g.
33.
How many moles of atoms are in 50.15 g of mercury (atomic mass 200.59 amu)?
Correct Answer
C. 0.2500 mol
Explanation
The molar mass of mercury is 200.59 g/mol. To find the number of moles, divide the given mass (50.15 g) by the molar mass. 50.15 g / 200.59 g/mol = 0.2500 mol. Therefore, there are 0.2500 moles of atoms in 50.15 g of mercury.
34.
A sample of tin (atomic mass 118.71 amu) contains 3.01 X 10^23 atoms. The mass of the sample is
Correct Answer
B. 59.3 g
Explanation
The mass of the sample can be calculated by multiplying the number of atoms by the atomic mass of tin. Since the sample contains 3.01 X 10^23 atoms and the atomic mass of tin is 118.71 amu, the mass of the sample is 3.01 X 10^23 atoms * 118.71 amu = 3.57 X 10^25 amu. To convert this to grams, we use the conversion factor 1 amu = 1.66 X 10^-24 g. Therefore, the mass of the sample is 3.57 X 10^25 amu * 1.66 X 10^-24 g/amu = 59.3 g.
35.
Because c, the speed of electromagnetic radiation is constant the wavelength of the radiation is
Correct Answer
C. Inversely proportional to its frequency
Explanation
The speed of electromagnetic radiation is constant, which means that as the frequency of the radiation increases, the wavelength decreases. This relationship is known as an inverse proportionality, where one value increases while the other value decreases. Therefore, the wavelength of the radiation is inversely proportional to its frequency.
36.
The frequency of electromagneticradiation is measured in waves/second, or
Correct Answer
C. Hertz
Explanation
The frequency of electromagnetic radiation is measured in hertz. Hertz is the unit of measurement for frequency and represents the number of cycles or waves per second. It is commonly used to describe the frequency of radio waves, light waves, and other forms of electromagnetic radiation. Nanometers, quanta, and joules are not units of frequency measurement, making hertz the correct answer.
37.
According to the particle model of light, certain kinds of light cannot eject electrons from metals because
Correct Answer
C. The energy of the light is too low.
Explanation
According to the particle model of light, certain kinds of light cannot eject electrons from metals because the energy of the light is too low. In this model, light is considered to be made up of particles called photons. When light interacts with a metal, the photons transfer their energy to the electrons in the metal. In order for an electron to be ejected from the metal, it needs to absorb enough energy from the photons. If the energy of the light is too low, the electrons will not have enough energy to overcome the binding forces of the metal and be ejected.
38.
Max Planck proposed that a hot object radiated energy in small, specific amounts called
Correct Answer
A. Quanta
Explanation
Max Planck proposed the concept of quanta, which refers to the idea that energy is emitted or absorbed in discrete packets rather than in a continuous manner. This theory revolutionized the understanding of energy and laid the foundation for the development of quantum mechanics. The term "quanta" is used to describe these specific amounts of energy, and it accurately represents Planck's groundbreaking concept.
39.
The energy of a photon is related to its
Correct Answer
C. Frequency
Explanation
The energy of a photon is related to its frequency. This is explained by the equation E = hf, where E represents the energy of the photon, h is Planck's constant, and f is the frequency of the photon. This equation shows that as the frequency increases, the energy of the photon also increases. Therefore, frequency is directly proportional to the energy of a photon.
40.
The emission of electrons from metals that have absorbed photons is called the
Correct Answer
B. pHotoelectric effect
Explanation
The photoelectric effect refers to the emission of electrons from metals that have absorbed photons. When photons strike the surface of a metal, they transfer their energy to the electrons, causing them to be ejected from the metal. This phenomenon was first explained by Albert Einstein and is a fundamental principle of quantum physics. The interference effect, quantum effect, and dual effect are not related to the emission of electrons from metals due to photon absorption.
41.
For an electron in an atom to change from the grround state to an excited state,
Correct Answer
B. Energy must be absorbed.
Explanation
When an electron in an atom changes from the ground state to an excited state, it requires energy to move to a higher energy level. This energy is absorbed by the electron, causing it to transition to the excited state.
42.
According to the Bohr model of the atom, the single electron of a hydrogen atom circles the nucleus
Correct Answer
A. In specific allowed orbits
Explanation
The Bohr model of the atom states that the single electron of a hydrogen atom moves in specific allowed orbits around the nucleus. These orbits are quantized, meaning that the electron can only occupy certain energy levels or distances from the nucleus. This model explains the stability of the atom and the emission or absorption of energy when the electron transitions between these orbits. Therefore, the correct answer is "in specific allowed orbits."
43.
The change of an atom from an excited state to the ground state always requires
Correct Answer
B. Emission of electromagnetic radiation
Explanation
When an atom transitions from an excited state to the ground state, it releases excess energy in the form of electromagnetic radiation. This radiation can be in various forms, including visible light. The emission of electromagnetic radiation is a fundamental process that occurs when an atom returns to a lower energy level, releasing the energy it had previously absorbed.
44.
The equation E= hv helped Louis de Broglie determine
Correct Answer
B. How electron wave frequencies correspond to specific energies
Explanation
The equation E= hv, where E is energy, h is Planck's constant, and v is frequency, relates the frequency of a wave to its energy. Louis de Broglie used this equation to determine how electron wave frequencies correspond to specific energies. This relationship is fundamental to understanding the behavior of electrons and their energy levels in an atom.
45.
Which model of the atom explains why excited hydrogen gas gives off certain colors of light?
Correct Answer
A. The Bohr model
Explanation
The Bohr model of the atom explains why excited hydrogen gas gives off certain colors of light. According to this model, electrons in hydrogen atoms exist in specific energy levels or orbits around the nucleus. When an electron absorbs energy, it moves to a higher energy level. However, it is unstable in this higher energy state and quickly returns to its original energy level, releasing the excess energy as light. The specific colors of light emitted correspond to the specific energy differences between the electron's orbits.
46.
Which model of the atom explains the orbitals of electrons as waves?
Correct Answer
B. The quantum model
Explanation
The quantum model of the atom explains the orbitals of electrons as waves. This model, also known as the quantum mechanical model or the wave mechanical model, is based on the principles of quantum mechanics. It describes electrons as wave-like particles that exist in specific energy levels or orbitals around the nucleus. These orbitals are represented as probability clouds, indicating the likelihood of finding an electron in a particular region of space. The quantum model provides a more accurate and comprehensive understanding of atomic behavior compared to previous models such as the Bohr model or Rutherford's model.
47.
The size and shape of an electron cloud are most closely related to the electron's
Correct Answer
D. Energy
Explanation
The size and shape of an electron cloud are most closely related to the electron's energy. This is because the energy of an electron determines its position and movement within the atom. The electron cloud represents the region where an electron is most likely to be found, and this cloud can expand or contract depending on the energy level of the electron. Higher energy levels correspond to larger and more diffuse electron clouds, while lower energy levels result in smaller and more compact electron clouds. Therefore, the energy of an electron directly influences the size and shape of its electron cloud.
48.
All of the following describe the Heisenberg uncertainty principle except
Correct Answer
D. It helps to locate an electron in an atom.
Explanation
The Heisenberg uncertainty principle does not help to locate an electron in an atom. Instead, it states that it is impossible to determine both the position and velocity of an electron simultaneously. It is one of the fundamental principles of our understanding of light and matter, and it helped lay the foundation for the modern quantum theory.
49.
All of the following describe the Schrodinger wave equation except
Correct Answer
D. It is similar to Bohr's theory.
Explanation
The Schrodinger wave equation is not similar to Bohr's theory. While Bohr's theory describes electrons in atoms as orbiting the nucleus in specific energy levels, the Schrodinger wave equation treats electrons as waves that exist in a probability cloud around the nucleus. The equation helped lay the foundation for the modern quantum theory by providing a mathematical description of the behavior of particles at the atomic level. It also allows for the calculation of the probability distribution of finding an electron in a certain region of space.
50.
The quantum number that indicates the position of an orbital about the three axes in space is the
Correct Answer
C. Magnetic quantum number
Explanation
The magnetic quantum number indicates the position of an orbital about the three axes in space. It determines the orientation of the orbital in a magnetic field and can have values ranging from -l to +l, where l is the azimuthal quantum number. The magnetic quantum number helps to describe the shape and orientation of an orbital within a specific energy level or shell.