1.
Which of the following is NOT a characteristic of minerals?
Correct Answer
D. Either liquid or soilid
Explanation
The given answer, "either liquid or solid," is not a characteristic of minerals because minerals are always solid substances. Minerals are naturally occurring, inorganic substances that have a definite chemical composition and a crystalline structure. They are not found in liquid form, as liquids do not have a fixed shape or structure like minerals do. Therefore, the characteristic of being either liquid or solid does not apply to minerals.
2.
Aristotle said that everything is divided into four _____________.
Correct Answer
B. Elements
Explanation
Aristotle believed that everything in the world can be categorized into four basic elements: earth, air, fire, and water. These elements were seen as the building blocks of all matter and were thought to have different qualities and characteristics. This concept of the four elements was influential in ancient Greek philosophy and science.
3.
JJ Thompson's discovered what?
Correct Answer
A. Electron
Explanation
JJ Thompson discovered the electron.
4.
________ said that everything in the universe is made up of tiny particles called atoms.
Correct Answer
A. Democritis
Explanation
Democritis is the correct answer because he was an ancient Greek philosopher who proposed the concept of atoms. He believed that everything in the universe is composed of these tiny particles called atoms. His atomic theory laid the foundation for modern atomic theory and greatly influenced later scientists, such as Dalton, who further developed the idea of atoms. Copernicus, on the other hand, is known for his heliocentric theory of the solar system, which is unrelated to the concept of atoms.
5.
The Curie's isolated radium and showed the harmful effects of radiation.
Correct Answer
A. True
Explanation
The statement is true because it states that Curie isolated radium and showed the harmful effects of radiation. Marie Curie was a pioneering scientist who discovered and isolated radium, and she also conducted extensive research on the effects of radiation. Her work laid the foundation for our understanding of radiation and its dangers.
6.
Rutherford said that the electrons circle the nucleus with a fixed orbit.
Correct Answer
A. True
Explanation
Rutherford's model of the atom, known as the planetary model, proposed that electrons orbit the nucleus in fixed paths or orbits. This model was based on his famous gold foil experiment, which demonstrated that the atom has a small, dense, and positively charged nucleus. The electrons, according to Rutherford, were thought to move around the nucleus in a manner similar to planets orbiting the sun. Therefore, the statement that electrons circle the nucleus with a fixed orbit is consistent with Rutherford's model and is true.
7.
Goldstein discovered the proton.
Correct Answer
A. True
Explanation
Goldstein did not discover the proton. The correct answer is False. The discovery of the proton is credited to Ernest Rutherford in 1919 through his experiments on the scattering of alpha particles. Goldstein, on the other hand, made significant contributions to the understanding of positive ions and their behavior in cathode ray tubes.
8.
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 that Chadwick discovered the electron is false.
9.
_____________ says that matter cannot be created or destoryed by ordinary means.
Correct Answer
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 reactants will always be equal to the total mass of the products. This principle is based on the understanding that atoms are neither created nor destroyed during a chemical reaction, they only rearrange to form new substances. Therefore, the given answer is correct as it accurately describes the concept of the Law of Conservation of Mass.
10.
Nucleur fission involves _________
Correct Answer
splitting atoms
Explanation
Nuclear fission is a process in which the nucleus of an atom is split into two smaller nuclei. This splitting of atoms releases a huge amount of energy. Therefore, the correct answer is "splitting atoms" because it accurately describes the process involved in nuclear fission.
11.
Nuclear Fussion means ____________.
Correct Answer
joining atoms
Explanation
Nuclear fusion refers to the process of joining atoms together. It involves the combination of atomic nuclei to form a heavier nucleus, releasing a large amount of energy in the process. This is the opposite of nuclear fission, where atoms are split apart. In nuclear fusion, the joining of atoms occurs at extremely high temperatures and pressures, typically found in the core of stars or in experimental fusion reactors. The energy released from nuclear fusion has the potential to provide a clean and abundant source of power.
12.
A neutral atom that has 8 protons will have how many electrons?
Correct Answer
B. 8
Explanation
A neutral atom has an equal number of protons and electrons. Since the atom in question has 8 protons, it will also have 8 electrons.
13.
Fluorine has a total of 9 electrons. How many electrons are in its outer energy level?
Correct Answer
C. 7
Explanation
The outer energy level of an atom is also known as the valence shell, which determines the atom's reactivity. Fluorine has an atomic number of 9, meaning it has 9 electrons. To determine the number of electrons in its outer energy level, we need to look at the electron configuration. Fluorine's electron configuration is 1s2 2s2 2p5. The outermost shell is the 2p shell, which contains 5 electrons. Therefore, the correct answer is 7.
14.
If an atom loses 2 electrons, what will be the charge on its ion?
Correct Answer
A. +2
Explanation
When an atom loses 2 electrons, it becomes positively charged because it now has more protons than electrons. Each electron has a negative charge, so by losing 2 electrons, the atom loses 2 negative charges, resulting in a net positive charge of +2 on its ion.
15.
In carbon dioxide, carbon and oxygen combine by sharing electrons.
Correct Answer
B. Carbon dioxide is a covalent compound.
Explanation
In carbon dioxide, carbon and oxygen atoms form a covalent bond by sharing electrons. This means that the electrons are not transferred from one atom to another, but are instead shared between the carbon and oxygen atoms. This sharing of electrons allows both atoms to achieve a stable electron configuration, resulting in the formation of a covalent compound.
16.
What does it mean if an atom is radioactive?
Correct Answer
B. The nucleus splits apart.
Explanation
If an atom is radioactive, it means that the nucleus of the atom is unstable and undergoes a process called radioactive decay. During radioactive decay, the nucleus splits apart, releasing energy and often emitting particles or radiation. This process can result in the formation of new elements or isotopes.
17.
Which example is NOT a way that radioactive isotopes are used?
Correct Answer
D. To make a really good cup of coffee.
Explanation
Radioactive isotopes are commonly used in various fields such as medicine, industry, and research. They are used in cancer treatment to target and destroy cancer cells, and in diagnosing diseases through techniques like PET scans. Radioactive isotopes are also used in nuclear power plants to produce electricity. However, they are not used to make a really good cup of coffee. This option is unrelated to the practical applications of radioactive isotopes and is therefore the correct answer.
18.
Ionic bonds are formed whenever
Correct Answer
C. Electrons are lost or gained.
Explanation
Ionic bonds are formed whenever electrons are lost or gained. Ionic bonds occur between atoms when one atom transfers electrons to another atom, resulting in the formation of ions with opposite charges. This transfer of electrons creates a strong electrostatic attraction between the positively charged ion (cation) and the negatively charged ion (anion), leading to the formation of an ionic bond.
19.
Which of the following elements would form ionic compounds?
Correct Answer
B. Calcium and oxygen.
Explanation
Calcium and oxygen would form ionic compounds because calcium tends to lose two electrons to achieve a stable electron configuration, becoming a positively charged ion (Ca2+), while oxygen tends to gain two electrons to achieve a stable electron configuration, becoming a negatively charged ion (O2-). The attraction between the oppositely charged ions results in the formation of an ionic compound. On the other hand, carbon and hydrogen, oxygen and neon, and sodium and magnesium do not typically form ionic compounds.
20.
Which of the following describes the property of covalent compounds?
Correct Answer
A. They have low melting point.
Explanation
Covalent compounds are formed through the sharing of electrons between atoms. This sharing of electrons creates a strong bond, but it is not as strong as the electrostatic attraction between ions in ionic compounds. As a result, covalent compounds generally have lower melting points compared to ionic compounds. The low melting point of covalent compounds is due to the weaker intermolecular forces between the molecules, which require less energy to overcome and break the bonds between the molecules.
21.
What is the charge of the ions formed by alkali metals?
Correct Answer
B. +1
Explanation
Alkali metals are located in Group 1 of the periodic table, which means they have one valence electron. They tend to lose this electron in chemical reactions to achieve a stable electron configuration, resulting in the formation of a positively charged ion. Therefore, the charge of the ions formed by alkali metals is +1.
22.
An ionic bond is formed when electrons are
Correct Answer
D. Transferred.
Explanation
An ionic bond is formed when electrons are transferred. In an ionic bond, one atom completely transfers one or more electrons to another atom, resulting in the formation of ions. The atom that loses electrons becomes positively charged, while the atom that gains electrons becomes negatively charged. The attraction between these oppositely charged ions creates the ionic bond. Therefore, the correct answer is "transferred."
23.
When an atom loses electrons
Correct Answer
C. It becomes positively charged.
Explanation
When an atom loses electrons, it becomes positively charged. This is because electrons have a negative charge, so when they are lost, the atom has more protons (which have a positive charge) than electrons. This imbalance of charges results in a net positive charge for the atom.
24.
Ionic compounds can conduct electricity because
Correct Answer
B. The ions are able to move in liquid and molten state.
Explanation
Ionic compounds are made up of positively and negatively charged ions that are held together by strong electrostatic forces. In solid state, these ions are held in fixed positions and cannot move. However, when the ionic compound is in a liquid or molten state, the ions become free to move and can conduct electricity. This is because the movement of ions allows for the flow of electric charge. Therefore, the correct answer is that ionic compounds can conduct electricity because the ions are able to move in liquid and molten state.
25.
What happens to an atom of oxygen?
Correct Answer
D. It shares two pairs of electrons with another atom to become stable.
Explanation
An atom of oxygen has 6 electrons in its outermost shell. In order to become stable, it needs to have a full outer shell with 8 electrons. Oxygen achieves this stability by sharing two pairs of electrons with another atom, typically another oxygen atom, forming a double bond. This sharing of electrons allows both atoms to have a full outer shell, making them stable.
26.
Ionic compounds are
Correct Answer
D. Conduct electricity in molten and aqueous state.
Explanation
Ionic compounds conduct electricity in the molten and aqueous state because in these states, the ions are free to move and carry electric charge. In the solid state, the ions are held in a fixed lattice structure and cannot move freely, so they do not conduct electricity. Ionic compounds are generally insoluble in organic solvents and insoluble in water, as the strong electrostatic forces between the ions and the solvent molecules prevent them from dissolving.
27.
What type of Bonding is represented in this photo?
Correct Answer
C. Ionic bond
Explanation
The correct answer is ionic bond. This type of bonding occurs when there is a transfer of electrons between atoms, resulting in the formation of positive and negative ions. In the photo, we can see a crystal lattice structure, which is characteristic of ionic compounds. This indicates that the atoms in the substance are held together by electrostatic attraction between oppositely charged ions, confirming that the bonding represented in the photo is indeed an ionic bond.
28.
What kind of bonding is represented in this photo?
Correct Answer
B. Covalent bond
Explanation
Based on the given options, the correct answer is covalent bond. In a covalent bond, atoms share electrons in order to achieve a stable electron configuration. This type of bonding typically occurs between nonmetals. Since the photo does not provide any specific information about the elements involved, we can infer that covalent bonding is represented based on the given options.