Nokea
What type of chemical reaction involves the reaction of a compound with oxygen?
- A. Decomposition
- B. Synthesis
- C. Combustion
- D. Single replacement
Correct Answer: C
Rationale: The correct answer is C: Combustion. A combustion reaction is characterized by a compound reacting with oxygen. During this process, heat and light are often produced as energy is released in the form of heat. Combustion is a common type of reaction involving organic compounds, like hydrocarbons, reacting with oxygen to produce carbon dioxide and water. Choices A, B, and D are incorrect because decomposition involves a compound breaking down into simpler substances, synthesis involves the combination of two or more substances to form a more complex one, and single replacement involves an element replacing another element in a compound.
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What is the process of breaking bonds and forming new bonds to create new chemical compounds?
- A. Physical reaction
- B. Chemical reaction
- C. Nuclear reaction
- D. Mechanical reaction
Correct Answer: B
Rationale: A chemical reaction involves the breaking and forming of bonds to create new substances. During a chemical reaction, the original chemical bonds are broken, and new bonds are formed to produce one or more new substances with different properties from the reactants. This transformation is a fundamental concept in chemistry and distinguishes chemical reactions from physical, nuclear, or mechanical reactions. Choice A, 'Physical reaction,' does not involve the breaking and forming of chemical bonds but rather changes in physical state or appearance. Choice C, 'Nuclear reaction,' involves changes in the nuclei of atoms, not the breaking and forming of chemical bonds. Choice D, 'Mechanical reaction,' refers to reactions involving physical forces or movements, not the breaking and forming of chemical bonds as in a chemical reaction.
What are positively charged ions called?
- A. Neutrons
- B. Protons
- C. Cations
- D. Electrons
Correct Answer: C
Rationale: Positively charged ions are called cations. When an atom loses electrons, it becomes positively charged and is referred to as a cation. Neutrons are neutral particles found in the nucleus of an atom, not charged. Protons are positively charged particles in the nucleus. Electrons are negatively charged particles orbiting the nucleus, not positively charged ions.
What charge do Group IA elements have?
- A. +1
- B. +2
- C. +3
Correct Answer: A
Rationale: Group IA elements, also known as alkali metals, have a +1 charge. They readily lose one electron to achieve a stable electron configuration, forming ions with a single positive charge. This makes +1 the correct choice. Choices B, C, and D are incorrect because alkali metals in Group IA typically lose one electron, so they do not have a +2, +3, or 0 charge.
What charge do Group IIA elements typically have?
- A. 1
- B. +2
- C. -3
Correct Answer: B
Rationale: Group IIA elements belong to the alkaline earth metals group in the periodic table. These elements typically have a charge of +2 because they readily lose two electrons to achieve a stable electron configuration. Therefore, the correct answer is B - +2. Choice A (1) is incorrect because Group IIA elements lose two electrons, not one. Choice C (-3) is incorrect because Group IIA elements do not gain electrons to have a negative charge. Choice D (0) is incorrect because Group IIA elements do lose electrons and have a positive charge, not a neutral charge.
Which law states that matter can neither be created nor destroyed during a chemical reaction?
- A. Law of Conservation of Energy
- B. Law of Conservation of Mass
- C. Law of Constant Composition
- D. Law of Multiple Proportions
Correct Answer: B
Rationale: The correct answer is B, the Law of Conservation of Mass. This law, formulated by Antoine Lavoisier, states that matter cannot be created or destroyed in a chemical reaction. It is a fundamental principle in chemistry that explains the preservation of mass during chemical reactions, indicating that the total mass of the reactants is equal to the total mass of the products. The other choices are incorrect because:
A: The Law of Conservation of Energy states that energy cannot be created or destroyed, not matter.
C: The Law of Constant Composition refers to compounds having the same composition by mass regardless of their source or how they were prepared, not about the conservation of matter in reactions.
D: The Law of Multiple Proportions describes the ratios in which elements combine to form compounds, not the conservation of mass.