Nokea
What charge do Group VIA elements typically have?
- A. -1
- B. -2
- C. -3
Correct Answer: B
Rationale: Group VIA elements, also known as Group 16 elements, typically have a charge of -2. This is because they have 6 valence electrons and tend to gain 2 electrons to achieve a stable octet configuration, resulting in a -2 charge. Choice A (-1) is incorrect as Group VIA elements need to gain 2 electrons for stability, not just 1. Choice C (-3) is incorrect because Group VIA elements do not need to gain 3 electrons to achieve stability. Choice D (0) is incorrect as Group VIA elements need to gain electrons to reach a stable configuration, resulting in a negative charge.
You may also like to solve these questions
Which branch of chemistry deals with the quantities and numeric relationships between compounds in a chemical reaction?
- A. Stoichiometry
- B. Molecular chemistry
- C. Atomic chemistry
- D. Thermodynamics
Correct Answer: A
Rationale: Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It involves the calculation of quantities of substances consumed and produced in a chemical reaction based on the balanced chemical equation.
Choice B, 'Molecular chemistry,' is incorrect as it focuses on the structure, properties, and reactions of molecules. Choice C, 'Atomic chemistry,' is incorrect as it primarily deals with the study of atoms and their interactions. Choice D, 'Thermodynamics,' is incorrect as it pertains to the study of energy and heat transfer in chemical and physical processes.
Which type of radiation involves the emission of helium ions?
- A. Beta
- B. Alpha
- C. Gamma
- D. Delta
Correct Answer: B
Rationale: Alpha radiation involves the emission of helium ions. Helium ions are composed of two protons and two neutrons, which is the same as the nucleus of a helium atom. This type of radiation has low penetration power and can be stopped by a piece of paper or human skin, making it less harmful compared to other forms of radiation like beta or gamma radiation. Beta radiation involves the emission of high-speed electrons, while gamma radiation involves electromagnetic waves with high energy. Delta radiation is not a recognized form of radiation in this context, making it an incorrect choice.
What can stop the penetration of alpha particles?
- A. Aluminum foil
- B. Glass
- C. Piece of paper
- D. Plastic
Correct Answer: C
Rationale: Alpha particles can be stopped by a piece of paper due to their low penetration power. The paper acts as a shield, effectively blocking the alpha particles from passing through. In contrast, materials like aluminum foil, glass, and plastic are not as effective as a simple piece of paper in stopping alpha particles. Aluminum foil is more effective against beta particles, gamma rays, and x-rays due to its higher density. Glass and plastic also provide some protection against beta particles and gamma rays, but they are less effective than a piece of paper against alpha particles.
Which number represents the number of protons in an element?
- A. Atomic mass
- B. Mass number
- C. Atomic number
- D. Proton number
Correct Answer: C
Rationale: The correct answer is C: Atomic number. The atomic number corresponds to the number of protons in an element. Protons are positively charged subatomic particles found in the nucleus of an atom. Each element has a unique atomic number, which defines its identity based on the number of protons it contains. Choice A, Atomic mass, is incorrect as it refers to the average mass of an atom of an element. Choice B, Mass number, represents the total number of protons and neutrons in an atom's nucleus. Choice D, Proton number, is not a commonly used term in chemistry to indicate the number of protons.
Which type of chemical reaction involves an active metal reacting with an ionic compound to create a new compound?
- A. Combustion
- B. Single replacement
- C. Synthesis
- D. Decomposition
Correct Answer: B
Rationale: The correct answer is 'Single replacement.' In a single replacement reaction, an active metal replaces another element in an ionic compound, resulting in the formation of a new compound. Option A, 'Combustion,' involves a substance rapidly reacting with oxygen to release energy in the form of heat and light. Option C, 'Synthesis,' involves the combination of two or more substances to form a more complex product. Option D, 'Decomposition,' involves the breakdown of a compound into simpler substances.