1.
The electron has no mass
Correct Answer
B. False
Explanation
This statement is false. The electron does have mass, although it is very small compared to other particles. The mass of an electron is approximately 9.11 x 10^-31 kilograms.
2.
The red photons found in the emission spectrum of atomic hydrogen are less energetic than the purple photons
Correct Answer
A. True
Explanation
The red photons found in the emission spectrum of atomic hydrogen are less energetic than the purple photons. This is because the energy of a photon is directly proportional to its frequency, and the frequency of red light is lower than that of purple light. Therefore, red photons have less energy than purple photons.
3.
The rare, backward reflection of alpha particles convinced Rutheford that the atom consisted of a dense, positively- charged nucleus.
Correct Answer
A. True
Explanation
The rare, backward reflection of alpha particles suggests that they were encountering a dense, positively-charged nucleus. This observation led Rutherford to conclude that the atom consists of a dense, positively-charged nucleus. Therefore, the statement is true.
4.
In gas discharge tube experiments, positive fragments from different types of atoms are similar to one another.
Correct Answer
B. False
Explanation
Gas discharge tube experiments involve passing an electric current through a gas-filled tube. When the gas molecules are ionized, they break apart into positive and negative fragments. These fragments are not similar to one another because they come from different types of atoms. Each atom has a unique number of protons, which determines its identity, so the positive fragments from different atoms will have different properties. Therefore, the statement that positive fragments from different types of atoms are similar to one another is false.
5.
To explain the continuous spectrum, Planck proposed that light could only be absorbed or emitted in discrete amounts.
Correct Answer
A. True
Explanation
Planck's proposal suggests that light can only be absorbed or emitted in discrete amounts, which means that energy is quantized. This concept is known as the quantization of energy. According to this idea, light can only exist in specific energy levels, and transitions between these levels result in the emission or absorption of photons. This explanation supports the statement that the continuous spectrum is true because it aligns with Planck's proposal of energy quantization.
6.
Bohr failed to explain why an accelerated electron does not radiate energy.
Correct Answer
A. True
Explanation
Bohr's atomic model, which is based on classical physics, fails to explain why an accelerated electron does not radiate energy. According to classical electromagnetic theory, any charged particle that undergoes acceleration should emit electromagnetic radiation. However, Bohr's model suggests that electrons in certain energy levels do not lose energy as they move in orbits around the nucleus. This discrepancy between classical physics and Bohr's model highlights the limitations of classical physics in describing the behavior of subatomic particles and the need for quantum mechanics to provide a more accurate explanation.
7.
Rutherford fully expected alpha particles to bounce off of the gold foil.
Correct Answer
B. False
Explanation
Rutherford did not expect alpha particles to bounce off of the gold foil. In fact, he expected most of the alpha particles to pass straight through the foil with only a small deflection. However, he was surprised to observe that a few alpha particles were deflected at large angles, which led to the discovery of the atomic nucleus. Therefore, the statement that Rutherford fully expected alpha particles to bounce off of the gold foil is false.
8.
The nucleus of an atom occupies more than half of the atom's volume.
Correct Answer
B. False
Explanation
The nucleus of an atom is located at the center and contains protons and neutrons. It is extremely small compared to the overall size of the atom. The majority of the atom's volume is occupied by the electron cloud, which consists of electrons orbiting the nucleus. Therefore, the statement that the nucleus occupies more than half of the atom's volume is false.
9.
The color of a hot object is related to its temperature.
Correct Answer
A. True
Explanation
The color of a hot object is related to its temperature because as an object's temperature increases, it emits more energy in the form of light. This light can range in color from red to white to blue, depending on the temperature. For example, a relatively cooler object will emit red light, while a hotter object will emit blue light. This phenomenon is known as blackbody radiation and is explained by Planck's law. Therefore, the statement "The color of a hot object is related to its temperature" is true.
10.
Dense, positively- charged center of the atom.
Correct Answer
Nucleus
Explanation
The correct answer is nucleus. The nucleus is the dense, positively-charged center of an atom. It contains protons and neutrons, which make up most of the atom's mass. The electrons orbit around the nucleus in energy levels.
11.
Rutherford model
Correct Answer
Solar system model
Explanation
The Rutherford model, also known as the solar system model, is an atomic model proposed by Ernest Rutherford in 1911. It suggests that the atom consists of a dense, positively charged nucleus at the center, with negatively charged electrons orbiting around it in fixed paths, similar to planets orbiting the sun in the solar system. This model explains the distribution of charge in an atom and the stability of the atom, as well as the behavior of alpha particles in the gold foil experiment.
12.
Spectra in which the colors of light change abruptly and many colors are missing
Correct Answer
Discrete spectra
Explanation
Discrete spectra refers to spectra where the colors of light change abruptly and many colors are missing. This means that the spectrum consists of distinct, separate lines or bands of colors, with gaps in between. This is in contrast to continuous spectra, where the colors blend smoothly into each other without any gaps. Discrete spectra can occur in various contexts, such as the emission spectra of certain elements or the absorption spectra of certain compounds.
13.
Thomson Model
Correct Answer
Plum pudding model
Explanation
The correct answer is Plum pudding model. The Thomson Model, also known as the Plum pudding model, was proposed by J.J. Thomson in 1904. According to this model, an atom consists of a positively charged sphere with negatively charged electrons embedded in it, resembling a plum pudding. This model helped to explain the overall neutrality of the atom and the presence of electrons, but it was later replaced by the Rutherford model after the discovery of the nucleus.
14.
Positively charged particle emitted by some radioactive materials
Correct Answer
Alpha particle
Explanation
Alpha particles are positively charged particles that are emitted by certain radioactive materials. They consist of two protons and two neutrons, making them identical to the nucleus of a helium atom. Due to their positive charge and relatively large size, alpha particles have low penetrating power and can be easily stopped by a sheet of paper or a few centimeters of air. This makes them less harmful compared to other types of radiation such as beta particles or gamma rays.
15.
The conservation of ________ law explains why photon emission occurs when an electron drops from a high to a low energy state.
Correct Answer
energy
Explanation
The conservation of energy law explains why photon emission occurs when an electron drops from a high to a low energy state. This law states that energy cannot be created or destroyed, only transferred or transformed from one form to another. When an electron transitions from a higher energy level to a lower one, it releases the excess energy in the form of a photon. This conservation principle ensures that the total energy of the system remains constant.
16.
Thomson's and Millikan's experiments provided strong evidence for the atom's _________ nature.
Correct Answer
electrical
Explanation
Thomson's and Millikan's experiments provided strong evidence for the atom's electrical nature. Thomson's experiment, known as the cathode ray tube experiment, demonstrated the presence of negatively charged particles within atoms, which he called electrons. Millikan's oil drop experiment measured the charge of an electron, further confirming the electrical nature of atoms. These experiments collectively supported the understanding that atoms are composed of charged particles and have electrical properties.
17.
Rutherford's orbits were _________________: Bohr's orbits were __________.
Correct Answer
elliptical, circular
Explanation
Rutherford's orbits were elliptical, meaning they were shaped like elongated ovals. This suggests that the electrons in Rutherford's model of the atom moved in paths that were not perfectly round. On the other hand, Bohr's orbits were circular, indicating that the electrons in Bohr's model moved in perfect circles around the nucleus. This difference in shape between the two models reflects the advancements made by Bohr in understanding the structure of the atom.
18.
An electron with a large value of n in the Bohr model is ______________ from the nucleus and has ___________ of energy.
Correct Answer
far away from, lots of
Explanation
An electron with a large value of n in the Bohr model is far away from the nucleus and has lots of energy. In the Bohr model, the value of n represents the energy level or shell in which the electron is located. As the value of n increases, the electron moves further away from the nucleus, resulting in an increase in its distance from the nucleus. Additionally, the energy of an electron in the Bohr model is directly proportional to its distance from the nucleus, so an electron with a large value of n will have a higher energy level.
19.
The nature functions using discrete rather than continuous energy is an assumption of the _________ model.
Correct Answer
Bohr
Explanation
The assumption that the nature functions using discrete rather than continuous energy is a key feature of the Bohr model. In this model, electrons are arranged in specific energy levels or orbits around the nucleus, and they can only transition between these levels by absorbing or emitting discrete amounts of energy. This concept is fundamental to understanding the behavior of atoms and their emission or absorption spectra.
20.
Thomson's gas discharge experiments provide direct experimental evidence for the
Correct Answer
D. Idea that all atoms are made of charged particles
Explanation
Thomson's gas discharge experiments involved passing an electric current through a gas at low pressure, which resulted in the production of a glowing beam called a cathode ray. Thomson observed that the cathode ray was deflected by electric and magnetic fields, indicating that it was composed of charged particles. This provided direct experimental evidence for the idea that all atoms are made of charged particles, supporting the given answer.
21.
In the Thomson (plum pudding) model of the atom, an atom is described as
Correct Answer
A. A positive "pudding" with small lumps of negative charge distributed throughout
Explanation
The Thomson (plum pudding) model of the atom describes an atom as a positive "pudding" with small lumps of negative charge distributed throughout. This means that the atom is mostly positively charged, with the negative charges dispersed within it. This model was proposed by J.J. Thomson in the late 19th century based on his experiments with cathode rays. He discovered that atoms contain negatively charged particles, which he called electrons, and proposed that they were embedded within a positively charged sphere. This model was later replaced by the Rutherford model, which discovered the existence of a small, dense, positively charged nucleus at the center of the atom.
22.
In what model do electrons orbit the nucleus so that any orbit allowed by Newtonian physics can be occupied by an electron?
Correct Answer
C. Rutherfod or "solar system" model
Explanation
The correct answer is Rutherford or "solar system" model. In this model, electrons orbit the nucleus in a manner similar to how planets orbit the sun in the solar system. According to this model, electrons occupy specific energy levels or shells around the nucleus, and each energy level can only hold a certain number of electrons. This model was proposed by Ernest Rutherford based on his gold foil experiment, which showed that atoms have a small, dense, positively charged nucleus at the center.
23.
White light passes through a gas that absorbs some of the light. The spectrum of light that passes through the gas is then analyzed. The spectrum could best be described as
Correct Answer
C. A mostly continuous spectrum that is missing some colors
Explanation
When white light passes through a gas that absorbs some of the light, the spectrum of light that passes through the gas is analyzed. In this case, the spectrum could best be described as a mostly continuous spectrum that is missing some colors. This means that the spectrum will show a range of colors, but there will be certain colors that are absent due to the absorption of light by the gas. This is because the gas selectively absorbs certain wavelengths of light, resulting in a spectrum with gaps or missing colors.
24.
Gases emit light when they are energized by an electrical discharge. The light results when an electron
Correct Answer
B. "jumps" from one energy level down to a lower energy level
Explanation
When gases are energized by an electrical discharge, the electrons within the atoms gain energy. This energy causes the electrons to move to higher energy levels. However, these electrons are not stable in these higher energy levels and eventually "jump" back down to lower energy levels. When they do so, they release the excess energy in the form of light. Therefore, the correct answer is that the electron "jumps" from one energy level down to a lower energy level.