Nokea
What does the sum of protons and neutrons in an element represent?
- A. Atomic number
- B. Mass number
- C. Atomic mass
- D. Neutron number
Correct Answer: B
Rationale: The sum of protons and neutrons in an element is known as the mass number. The mass number is an important concept in chemistry as it represents the total number of nucleons (protons and neutrons) in an atom's nucleus. It is different from the atomic number, which represents the number of protons in an atom. The atomic mass is the average mass of an element's isotopes, taking into account the abundance of each isotope. Neutron number, on the other hand, specifically refers to the number of neutrons in an atom's nucleus. Therefore, the correct answer is B, mass number.
You may also like to solve these questions
What charge do Group VIIA elements have?
- A. -1
- B. -2
- D. 1
Correct Answer: A
Rationale: Group VIIA elements, also known as halogens, have a tendency to gain one electron to achieve a stable electron configuration, resulting in a -1 charge. This is because they have seven valence electrons and need one more to complete their octet, making them highly reactive in forming -1 ions. Therefore, the correct answer is A. Choice B (-2) is incorrect because Group VIIA elements typically gain one electron, not two. Choice C (0) is incorrect as these elements tend to form -1 ions by gaining one electron. Choice D (1) is incorrect because Group VIIA elements gain electrons to form negative ions, not positive ones.
What charge do alpha radiation particles have?
- A. -2
- C. +2
- D. +1
Correct Answer: C
Rationale: The correct answer is C: +2. Alpha radiation particles consist of two protons and two neutrons, giving them a net charge of +2. This positive charge is due to the presence of the two protons in the nucleus of the alpha particle. Choice A (-2) is incorrect as alpha particles have a positive charge. Choice B (0) is incorrect as alpha particles carry a charge. Choice D (+1) is incorrect as alpha particles have a higher positive charge due to the presence of two protons.
What are the horizontal rows of the periodic table called?
- A. Periods
- B. Families
- C. Groups
- D. Columns
Correct Answer: A
Rationale: The correct answer is A: Periods. Rows in the periodic table are called periods. They are arranged horizontally from left to right and represent the energy levels of the elements. Each period starts a new energy level or shell, indicating the number of electron shells an element has. Choices B, C, and D are incorrect. Families and groups refer to vertical columns in the periodic table that share similar chemical properties, while columns are vertical arrangements of elements known as groups or families.
Which of the following types of matter changes in volume with changes in temperature and pressure?
- A. Liquid
- B. Gas
- C. Solid
- D. Plasma
Correct Answer: B
Rationale: A gas changes its volume with changes in temperature and pressure due to the particles moving more rapidly at higher temperatures, and pressure affects the space between particles. Liquids have a relatively fixed volume but take the shape of their container. Solids have a definite shape and volume, so they do not change volume with changes in temperature and pressure. Plasma is a state of matter where particles are highly energized and do not have a fixed volume, but it does not exhibit volume changes with temperature and pressure variations.
How are elements arranged in the periodic table?
- A. By their atomic mass
- B. By their chemical properties
- C. By their physical state
- D. By their charge
Correct Answer: B
Rationale: Elements are arranged in the periodic table based on their chemical properties, making choice B the correct answer. The periodic table is organized so that elements with similar chemical properties are grouped together in columns, known as groups or families. This arrangement allows for the identification of trends in the behavior of elements and predicting their properties based on their position in the table. Choices A, C, and D are incorrect because the periodic table primarily focuses on the chemical properties of elements, not solely on atomic mass, physical state, or charge.