1.
________ said that everything in the universe is made up of tiny particles called atoms.
Correct Answer
A. Democritus
Explanation
Democritus is attributed with the statement that everything in the universe is made up of tiny particles called atoms. He was an ancient Greek philosopher who proposed the concept of atomism, suggesting that all matter is composed of indivisible and indestructible particles. His ideas laid the foundation for modern atomic theory and greatly influenced later scientific thinkers, including Dalton. Copernicus, on the other hand, is known for his heliocentric model of the solar system, while Aristotle made significant contributions to various fields but did not specifically propose the concept of atoms.
2.
Dalton reintroduced the concept of the atom and created _______ which was the basic concept of the molecule.
Correct Answer
B. Dalton's Atomic Theory
Explanation
Dalton reintroduced the concept of the atom and created his atomic theory, which became the basic concept of the molecule. This theory proposed that atoms are indivisible and indestructible particles, and that compounds are formed by the combination of atoms in specific ratios. Dalton's Atomic Theory laid the foundation for understanding the structure and behavior of matter at the atomic level, and it greatly influenced the development of modern chemistry.
3.
JJ Thompson discovered what?
Correct Answer
A. Electrons
Explanation
JJ Thompson discovered the electron using cathode ray tube experiments, allowing him to develop the plum pudding atomic model.
4.
Aristotle said that everything is divided into four _____________.
Correct Answer
B. Elements
Explanation
Aristotle believed everything in the world can be categorized into four fundamental elements: air, fire, earth, and water.
5.
Leeuwenhoek invented what?
Correct Answer
A. Microscope
Explanation
Leeuwenhoek is known for inventing the microscope. He was a Dutch scientist who made significant contributions to the field of microscopy. He developed a simple microscope with a single lens, which allowed him to observe and study microscopic organisms and structures for the first time. This invention revolutionized the field of biology and laid the foundation for the development of modern microscopes.
6.
Copernicus says that ____________________.
Correct Answer
B. The Earth revolves around the sun
Explanation
Copernicus was a famous astronomer who proposed the heliocentric model of the solar system, which states that the Earth revolves around the sun. This model challenged the prevailing belief at the time that the sun and other celestial bodies revolved around the Earth. Copernicus' theory revolutionized our understanding of the universe and laid the foundation for modern astronomy.
7.
Proust was involved with the ________________.
Correct Answer
A. Law of Definite Proportions
Explanation
Proust was involved with the Law of Definite Proportions. This law states that a compound always contains the same elements in the same proportion by mass. Proust's work in the late 18th century on chemical compounds, particularly his experiments on the composition of copper carbonate, led to the formulation of this law. He discovered that regardless of the amount of copper carbonate used, the ratio of copper to oxygen remained constant. This law laid the foundation for the development of stoichiometry and the understanding of chemical reactions.
8.
Wilhelm Rontgen discovered what?
Correct Answer
A. radioactivity and x-rays
Explanation
Wilhelm Röntgen's discovery specifically pertained to X-rays. He accidentally discovered X-rays while experimenting with cathode rays. This discovery was significant because it unveiled a new form of electromagnetic radiation that could penetrate various materials, including human tissue. Röntgen's work laid the foundation for the field of radiology and revolutionized medical diagnostics and imaging.
9.
Bohr's solar system model involved the electrons having (a) ____________.
Correct Answer
B. Changing orbit
Explanation
In Bohr's solar system model, the electrons are described as having changing orbits. This means that the electrons are not fixed in one position around the nucleus, but rather move in various orbits at different energy levels. This model suggests that electrons can transition between these orbits by either absorbing or emitting energy in discrete amounts, known as quanta. This concept of changing orbits was a significant departure from the classical understanding of electrons as particles moving in fixed orbits, and it played a crucial role in the development of quantum mechanics.
10.
Milliken said that the electron has
Correct Answer
C. A charge and a small mass
Explanation
Milliken's statement contradicts the commonly known fact that electrons have a negative charge and a small mass. Electrons are subatomic particles with a negative charge and a relatively small mass compared to other particles such as protons and neutrons. Therefore, the given answer is incorrect and does not align with scientific understanding.
11.
Ptolemy says the sun revolves around the Earth.
Correct Answer
A. True
Explanation
This answer is based on the historical understanding of astronomy during Ptolemy's time. Ptolemy, an ancient Greek astronomer, proposed the geocentric model of the universe, which stated that the Earth was at the center and all celestial bodies, including the sun, revolved around it. This model was widely accepted for centuries until the heliocentric model, which places the sun at the center, was proposed by Copernicus. Therefore, based on the historical context, the statement that Ptolemy says the sun revolves around the Earth is true.
12.
Galileo invented the Modern Atomic Theory.
Correct Answer
B. False
Explanation
Galileo did not invent the Modern Atomic Theory. The Modern Atomic Theory was developed by John Dalton in the early 19th century. Galileo, on the other hand, was a physicist and astronomer who made significant contributions to the fields of motion, astronomy, and the scientific method.
13.
The Curie's isolated radium and showed the harmful effects of radiation.
Correct Answer
A. True
Explanation
Curie's isolation of radium and her subsequent research on radiation demonstrated the harmful effects of radiation. Through her work, she discovered that exposure to radiation could cause serious health issues, such as burns, cancer, and even death. This groundbreaking research paved the way for further understanding of radiation and its dangers.
14.
Ruthorford said that the electrons circle the nucleus with a fixed orbit.
Correct Answer
B. False
Explanation
Ernest Rutherford proposed the nuclear model of the atom, where he described the atom as having a dense nucleus with electrons orbiting around it. However, he did not specify that electrons have fixed orbits. The concept of electrons in fixed orbits was introduced later by Niels Bohr in his Bohr model of the atom. Rutherford's model was primarily focused on the discovery of the nucleus and the general structure of the atom.
15.
Goldstein discovered the proton.
Correct Answer
B. False
Explanation
Goldstein did not discover the proton. The proton was actually discovered by Ernest Rutherford in 1919 through his famous gold foil experiment. Goldstein, on the other hand, is credited with the discovery of the proton's positively charged counterpart, the canal ray or positive ray. These rays were observed in a cathode ray tube and were found to be composed of positively charged particles, which were later identified as protons by Rutherford. Therefore, the correct answer is False.
16.
Chadwick discovered the electron
Correct Answer
B. False
Explanation
Chadwick did not discover the electron. The electron was actually discovered by J.J. Thomson in 1897 through his experiments with cathode rays. Chadwick, on the other hand, is credited with the discovery of the neutron in 1932. Therefore, the statement "Chadwick discovered the electron" is false.
17.
What is Avagadro's number?
Correct Answer
A. 6.02 x 10^23
Explanation
Avogadro's number is a fundamental constant in chemistry and physics that represents the number of atoms or molecules in one mole of a substance. It is approximately 6.02 x 10^23, which means that one mole of any substance contains 6.02 x 10^23 atoms or molecules. This number is derived from experiments and is used to relate the macroscopic properties of substances to their microscopic constituents.
18.
__________ is a standard number of chemical units such as atoms, molecules, ions and electrons
Correct Answer
A. Mole
Explanation
A mole is a standard number of chemical units such as atoms, molecules, ions, and electrons. It is a fundamental unit in chemistry that represents the amount of a substance. One mole of any substance contains Avogadro's number of particles, which is approximately 6.022 x 10^23. The mole allows scientists to easily compare and calculate the amounts of different substances in chemical reactions. It is a crucial concept in stoichiometry and plays a significant role in understanding the quantitative aspects of chemistry.
19.
Einstein's Theory of ______ involved E = MC^2
Correct Answer
A. Relativity
Explanation
Einstein's Theory of Relativity is the correct answer because it is the scientific theory that explains the relationship between energy (E), mass (M), and the speed of light (C). The equation E = MC^2, also known as the mass-energy equivalence, is a fundamental result of this theory. It states that energy and mass are interchangeable and that the energy of an object is equal to its mass multiplied by the speed of light squared. This theory revolutionized our understanding of space, time, and gravity.
20.
_____________ says that matter cannot be created or destroyed by ordinary means.
Correct Answer
A. Law of Conservation of Mass
Explanation
The Law of Conservation of Mass states that matter cannot be created or destroyed by ordinary means. This means that in any chemical reaction or physical change, the total mass of the substances involved remains constant. This principle is a fundamental concept in chemistry and is supported by numerous experimental observations. It is closely related to the Law of Conservation of Energy, which states that energy cannot be created or destroyed, but can only be converted from one form to another. The Second Law of Motion is unrelated to the conservation of mass.
21.
What does the E, M, and C mean in E = MC^2?
Correct Answer
A. E= Energy M= Mass C=Speed of light
Explanation
The correct answer is E= Energy, M= Mass, C= Speed of light. This equation, known as Einstein's mass-energy equivalence, states that energy (E) is equal to the mass (M) multiplied by the speed of light (C) squared. It shows that mass and energy are interchangeable and that a small amount of mass can be converted into a large amount of energy. This equation is a fundamental principle in physics and is used to understand various phenomena, such as nuclear reactions and the behavior of particles at high speeds.
22.
Nuclear fission involves
Correct Answer
A. Splitting atoms
Explanation
Nuclear fission is a process in which the nucleus of an atom is split into two smaller nuclei, releasing a large amount of energy. This process involves splitting atoms, as mentioned in the correct answer. The other options, joining atoms and scattering atoms, do not accurately describe the process of nuclear fission. Joining atoms refers to nuclear fusion, where two smaller nuclei combine to form a larger nucleus, while scattering atoms does not accurately describe any specific nuclear process. Therefore, the correct answer is splitting atoms.
23.
Atomic Mass Unit (amu) is equal to how much of a carbon-12 atom?
Correct Answer
A. 1/12 mass
Explanation
The correct answer is 1/12 mass. Atomic Mass Unit (amu) is a unit used to measure the mass of atoms and molecules. It is defined as 1/12th the mass of a carbon-12 atom. This means that a carbon-12 atom is assigned a mass of exactly 12 atomic mass units. Therefore, 1/12th of this mass is equal to 1 atomic mass unit.
24.
Nuclear fusion involves
Correct Answer
A. Joining of atoms
Explanation
Nuclear fusion involves the process of joining atoms together to form a heavier atom. This occurs at extremely high temperatures and pressures, where the atomic nuclei overcome their repulsive forces and merge, releasing a tremendous amount of energy in the process. Fusion is the process that powers the sun and other stars, and it holds the potential for clean and abundant energy production on Earth.
25.
What is an angstrom?
Correct Answer
A. 10^-8 cm
Explanation
An angstrom is a unit of length used to measure extremely small distances, especially in the field of atomic and molecular physics. It is equal to 10^-10 meters or 10^-8 centimeters.
26.
What is the average diameter of the nucleus?
Correct Answer
A. 10^-10 cm
Explanation
The average diameter of the nucleus is 10^-10 cm. This is the correct answer because the nucleus is the central part of an atom, containing protons and neutrons. It is extremely small in size, and its diameter is typically measured in femtometers (10^-15 m) or picometers (10^-12 m). The given answer of 10^-10 cm is equivalent to 10^-12 m, which falls within the typical range for the diameter of a nucleus.
27.
What is the average distance between atoms?
Correct Answer
A. 1 to 5 angstroms
Explanation
The average distance between atoms is typically measured in angstroms. The given answer range of 1 to 5 angstroms suggests that the average distance between atoms falls within this range. This range is commonly observed in various types of molecules and compounds, indicating the typical spacing between atoms in a variety of chemical structures.
28.
What is the average diameter of an atom?
Correct Answer
A. 5 angstrom
Explanation
The average diameter of an atom is commonly measured in angstroms. In this case, the correct answer is 5 angstroms. This suggests that, on average, atoms have a diameter of 5 angstroms.
29.
How is the nucleus held together?
Correct Answer
A. Nuclear forces
Explanation
The nucleus is held together by nuclear forces. These forces are the strong interactions between the protons and neutrons within the nucleus. They are responsible for binding the nucleons together and overcoming the electrostatic repulsion between the positively charged protons. Nuclear forces are much stronger than other types of forces such as ionic bonds, metallic bonds, or van der Waals forces, and they are specific to the nucleus and its constituents.
30.
What are the Van Der Waal Forces?
Correct Answer
A. Intermolecular forces
Explanation
Van der Waal forces refer to the weak attractive forces that exist between molecules or atoms. These forces arise due to temporary fluctuations in electron distribution, resulting in temporary dipoles. The interaction between these temporary dipoles leads to a weak attraction between the molecules or atoms. These forces are not ionic in nature, as they do not involve the transfer or sharing of electrons between atoms. Similarly, they are not nuclear forces, which are much stronger forces that exist within the nucleus of an atom. Therefore, the correct answer is "intermolecular forces.”