1.
Mass is anything that takes up space and has weight.
Correct Answer
A. True
Explanation
Mass is a fundamental property of matter that measures the amount of substance in an object. It is different from weight, which is the force exerted on an object due to gravity. Mass is an intrinsic property of an object and does not depend on its location or the presence of gravity. Therefore, anything that takes up space and has weight also has mass. Hence, the statement "Mass is anything that takes up space and has weight" is true.
2.
A molecule is two or more atoms bonded together.
Correct Answer
A. True
Explanation
A molecule is formed when two or more atoms combine and are held together by chemical bonds. This definition accurately describes the nature of a molecule, making the statement "A molecule is two or more atoms bonded together" true.
3.
A horizontal row of elements is a;
Correct Answer
B. Period
Explanation
A horizontal row of elements is called a period in the periodic table. Periods are numbered from 1 to 7 and represent the energy levels or shells of the atoms. Each period corresponds to the number of electron shells that the elements in that row have. As you move across a period from left to right, the number of protons and electrons increases, resulting in a gradual increase in atomic size and chemical properties. Therefore, the given answer, "period," accurately describes a horizontal row of elements in the periodic table.
4.
A horizontal row of elements is a;
Correct Answer
B. Period
Explanation
A horizontal row of elements is referred to as a "period" in the periodic table. The periodic table is organized in rows and columns, with each row representing a period. Each period corresponds to the number of electron shells that the elements in that row have. Therefore, the correct answer is "period."
5.
Protons have a __________________ charge.
Correct Answer
A. Positive
Explanation
Protons have a positive charge because they carry a fundamental unit of positive electric charge. They are one of the subatomic particles found in the nucleus of an atom, along with neutrons which have no charge, while electrons carry a negative charge and orbit around the nucleus. The positive charge of protons is essential for maintaining the overall electrical neutrality of an atom, as the number of protons is balanced by an equal number of negatively charged electrons.
6.
Neutrons have a __________________ charge.
Correct Answer
C. Neutral
Explanation
Neutrons have a neutral charge because they do not have a positive or negative charge. They are electrically neutral particles found in the nucleus of an atom, along with protons. Neutrons have a mass similar to protons but do not carry any electrical charge.
7.
Electrons have a __________________ charge.
Correct Answer
B. Negative
Explanation
Electrons have a negative charge because they are subatomic particles that carry a fundamental unit of negative electrical charge. This charge is equal in magnitude but opposite in sign to the positive charge of protons, which are the other subatomic particles found in atoms. The negative charge of electrons allows them to be attracted to and orbit around the positively charged nucleus of an atom.
8.
Plasma is a state of matter.
Correct Answer
A. True
Explanation
Plasma is indeed a state of matter. It is often referred to as the fourth state of matter, alongside solid, liquid, and gas. Plasma is formed when a gas is heated to such high temperatures that the electrons are stripped away from the atoms, creating a mixture of free electrons and positively charged ions. Plasma is commonly found in stars, lightning, and certain man-made devices such as plasma TVs and fluorescent lights. Its unique properties make it distinct from the other states of matter.
9.
A solid has a fixed volume.
Correct Answer
A. True
Explanation
A solid has a fixed volume because its particles are closely packed together and have a fixed arrangement. This means that the amount of space the solid occupies is constant, regardless of any external factors such as pressure or temperature. Unlike liquids and gases, solids do not easily compress or expand, which allows them to maintain a fixed volume.
10.
A solution may or may not be a solid.
Correct Answer
A. True
Explanation
A solution is a homogeneous mixture of two or more substances, where one substance is dissolved in another. It can be in the form of a liquid, gas, or even a solid. Therefore, a solution can be a solid if a solid substance is dissolved in a liquid or another solid substance. Hence, the statement "A solution may or may not be a solid" is true.
11.
When a substance is thoroughly dissolved in another substance the result is a mixture, which is called a _____________________.
Correct Answer
A. Solution
Explanation
When a substance is thoroughly dissolved in another substance, it forms a mixture known as a solution. In a solution, the substance that is being dissolved is called the solute, while the substance in which it is dissolved is called the solvent. The solute particles become evenly distributed throughout the solvent, resulting in a homogeneous mixture. This process of dissolution occurs at the molecular level, where the solute particles are surrounded and separated by the solvent particles. The term "syllabus" is unrelated to the concept of a dissolved substance and does not fit the context of the question.
12.
Water is known as a universal _____________________.
Correct Answer
C. Solvent
Explanation
Water is known as a universal solvent because it has the ability to dissolve a wide range of substances. This is due to its unique molecular structure, which allows it to form hydrogen bonds with other molecules. These hydrogen bonds break apart the solute particles and surround them with water molecules, effectively dissolving them. Water's ability to dissolve many different substances makes it essential for various biological and chemical processes, as well as for transportation of nutrients and waste in living organisms.
13.
The valence number is the number of electrons in an atom's ___________________ shell.
Correct Answer
B. Outer
Explanation
The valence number is the number of electrons in an atom's outer shell. This shell is also known as the valence shell, and it is the outermost shell of an atom. The electrons in the valence shell are involved in chemical bonding and determine the atom's reactivity and ability to form bonds with other atoms. Therefore, the correct answer is "outer."
14.
New elements are still being discovered.
Correct Answer
A. True
Explanation
The statement "New elements are still being discovered" implies that there are still elements that have not been identified or added to the periodic table. This is true as scientists continue to conduct research and experiments to discover and synthesize new elements. The discovery of new elements expands our understanding of the chemical world and contributes to advancements in various fields of science.
15.
What is a chemical reaction?
Correct Answer
C. Chemical bonds break and new ones form
Explanation
A chemical reaction refers to a process in which chemical bonds between atoms are broken and new bonds are formed, resulting in the transformation of substances into different ones. This process involves the rearrangement of atoms and the exchange or sharing of electrons to create new compounds with different properties. It is a fundamental concept in chemistry and is responsible for various natural and synthetic processes, including the formation of compounds, release or absorption of energy, and the occurrence of chemical changes in matter.
16.
One molecule of water, always contains two hydrogen atoms and ___________ oxygen atom(s).
Correct Answer
A. One
Explanation
The chemical formula for water is H2O, which means that each molecule of water contains two hydrogen atoms and one oxygen atom. The number of oxygen atoms in a water molecule is always one.
17.
Which of the following is not a physical change,
Correct Answer
B. Developing film
Explanation
Developing film is not a physical change because it involves a chemical process rather than a change in the physical properties of the film itself. During film development, the exposed silver halide crystals on the film react with chemicals to form a visible image. This chemical reaction alters the composition of the film, making it a chemical change rather than a physical one. On the other hand, painting a wall, boiling water, and shredding cheese are all examples of physical changes as they involve alterations in the physical properties of the substances without changing their chemical composition.
18.
The substance that is dissolved in a solution is known as the _____________________.
Correct Answer
B. Solute
Explanation
The substance that is dissolved in a solution is known as the solute. In a solution, the solute is the component that is present in a smaller quantity and gets dissolved in the solvent. The solute can be a solid, liquid, or gas, and it disperses evenly throughout the solvent to form a homogeneous mixture. The solute is responsible for giving the solution its properties and can be separated from the solvent through various methods such as evaporation or filtration.
19.
A group of atoms with the same number of protons, but a different number of ________________ are known as isotopes.
Correct Answer
C. Neutrons
Explanation
Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. Since the question is asking for the missing word that completes the sentence, the correct answer is "neutrons".
20.
The atomic number tells the number of ___________________ in an atom of that element.
Correct Answer
B. Protons
Explanation
The atomic number tells the number of protons in an atom of that element. Protons are positively charged particles found in the nucleus of an atom. The number of protons in an atom determines its identity as a specific element. Therefore, the atomic number is a fundamental property of each element and can be used to identify and differentiate between different elements.
21.
An atom without a charge, one that is not an ion has the same number of protons as ____________________.
Correct Answer
D. Electrons
Explanation
An atom without a charge, also known as a neutral atom, has the same number of protons as electrons. This is because in a neutral atom, the positive charge of the protons is balanced by the negative charge of the electrons, resulting in a net charge of zero. Therefore, the number of protons and electrons in a neutral atom is equal.
22.
Three things that can affect the dissolving rate are;
Correct Answer(s)
A. Size of particles being dissolved
C. Temperature
E. Amount of stirring
Explanation
The dissolving rate can be affected by the size of particles being dissolved because smaller particles have a larger surface area, allowing for more contact with the solvent. This increases the rate of dissolution. Temperature also affects the dissolving rate as higher temperatures provide more energy to break the bonds between solute particles, leading to faster dissolution. Lastly, the amount of stirring can impact the dissolving rate by ensuring that the solvent and solute are constantly in contact, speeding up the dissolution process. The thickness of the beaker and the size of the stirring stick are not mentioned as factors affecting the dissolving rate.
23.
Alloys are metals created by combining metallic elements.
Correct Answer
A. True
Explanation
Alloys are indeed metals that are formed by combining two or more metallic elements. This process allows for the enhancement of specific properties such as strength, durability, and resistance to corrosion. By mixing different metals, engineers and scientists can create alloys with unique characteristics that are not found in pure metals. Therefore, the statement "Alloys are metals created by combining metallic elements" is true.
24.
An ion is an atom that has a neutral charge.
Correct Answer
B. False
Explanation
An ion is an atom that has gained or lost electrons, resulting in a positive or negative charge. Therefore, it is not correct to say that an ion has a neutral charge.
25.
A bond shared when atoms share electrons is a covalent bond.
Correct Answer
A. True
Explanation
A covalent bond is formed when atoms share electrons. This type of bond occurs between nonmetal atoms, where they share one or more pairs of electrons to achieve a stable electron configuration. This sharing of electrons creates a strong bond between the atoms, resulting in the formation of molecules or compounds. Therefore, the statement that a bond shared when atoms share electrons is a covalent bond is true.
26.
The elements on the far right of the periodic table are called
Correct Answer
A. Noble gases
Explanation
The elements on the far right of the periodic table are called noble gases because they belong to Group 18 and have a full outer electron shell. This makes them very stable and unreactive, which is why they are often referred to as "noble." These gases include helium, neon, argon, krypton, xenon, and radon. They are colorless, odorless, and have low boiling points. Noble gases are used in various applications, such as lighting, lasers, and cryogenics.
27.
The difference between mass and weight is weight is a measure of the force of gravity pulling on an object and mass is the amount of matter in an object.
Correct Answer
A. True
Explanation
The explanation for the given correct answer is that weight is indeed a measure of the force of gravity pulling on an object, while mass refers to the amount of matter present in an object. Weight can vary depending on the strength of the gravitational force, whereas mass remains constant regardless of the gravitational field. Therefore, it is true that the difference between mass and weight lies in their definitions and how they are measured.
28.
What is malleability?
Correct Answer
B. A metal that is able to be pressed or hammered permanently out of shape without breaking or cracking
Explanation
Malleability refers to the ability of a metal to be easily deformed under compression without breaking or cracking. This means that the metal can be pressed or hammered into different shapes without losing its structural integrity. This property is essential in various industries, such as construction and manufacturing, where metals need to be molded or shaped according to specific requirements.
29.
An ionic bond is a rigid framework of many atoms bonded together.
Correct Answer
B. False
Explanation
An ionic bond is not a rigid framework of many atoms bonded together. Instead, it is a type of chemical bond that forms between ions of opposite charges. In an ionic bond, one atom transfers electrons to another atom, resulting in the formation of positively and negatively charged ions. These ions are held together by electrostatic attraction, rather than forming a rigid framework. Therefore, the statement that an ionic bond is a rigid framework of many atoms bonded together is false.
30.
Hydrogen bonds are weak bonds.
Correct Answer
A. True
Explanation
Hydrogen bonds are weak bonds because they are formed between a hydrogen atom and an electronegative atom such as oxygen, nitrogen, or fluorine. These bonds are not as strong as covalent or ionic bonds, but they are still important in many biological and chemical processes. Hydrogen bonds play a crucial role in the structure of molecules like DNA and proteins, as well as in the properties of water. Despite being weak individually, hydrogen bonds can collectively provide stability to larger structures and contribute to the overall strength and functionality of molecules.