Nokea
Balance the following redox reaction in acidic solution: Iâ» (aq) + Crâ‚‚O₇²â» (aq) -> Iâ‚‚ (aq) + Cr³âº (aq). Identify the oxidizing agent and reducing agent.
- A. Iâ» is oxidized, Crâ‚‚O₇²â» is reduced
- B. Iâ» is reduced, Crâ‚‚O₇²â» is oxidized
- C. Both Iâ» and Crâ‚‚O₇²â» are oxidized
- D. Both Iâ» and Crâ‚‚O₇²â» are reduced
Correct Answer: B
Rationale: In the given redox reaction, Iâ» is gaining electrons to form Iâ‚‚, which means Iâ» is being reduced (undergoing reduction). On the other hand, Crâ‚‚O₇²â» is losing electrons to form Cr³âº, indicating that Crâ‚‚O₇²â» is being oxidized (undergoing oxidation). Therefore, Iâ» is the reducing agent and Crâ‚‚O₇²â» is the oxidizing agent. Choice A is incorrect because Iâ» is being reduced, not oxidized. Choice C is incorrect as both species cannot be oxidized in the same reaction. Choice D is incorrect as both species cannot be reduced in the same reaction.
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What is the primary difference between ionic and metallic bonding?
- A. Ionic bonds involve electron transfer, while metallic bonds involve electron sharing.
- B. Ionic bonds are weak and directional, while metallic bonds are strong and non-directional.
- C. Ionic bonds exist between metals and non-metals, while metallic bonds exist only between metals.
- D. Ionic bonds form discrete molecules, while metallic bonds form extended structures.
Correct Answer: B
Rationale: Ionic bonds involve electron transfer, where one atom completely donates an electron to another, resulting in discrete molecules. On the other hand, metallic bonds are non-directional and strong, formed by a 'sea' of delocalized electrons shared among all metal atoms. This shared electron cloud allows for strong bonding throughout the entire material, making metallic bonds non-directional and strong compared to the directional and weaker nature of ionic bonds. Choice A is incorrect because metallic bonds do not involve electron sharing but rather the sharing of a sea of delocalized electrons. Choice C is incorrect as metallic bonds can also exist between metal atoms, not just between metals and non-metals. Choice D is incorrect because metallic bonds do not form discrete molecules but rather extended structures due to the sharing of electrons among all metal atoms.
What is the term for the process of a gas changing directly into a solid?
- A. Condensation
- B. Deposition
- C. Sublimation
- D. Evaporation
Correct Answer: B
Rationale: The correct term for the process of a gas changing directly into a solid is deposition. During deposition, gas particles lose energy and transition directly into the solid state without passing through the liquid phase. Sublimation, on the other hand, is the process in which a solid changes directly into a gas without going through the liquid phase. Condensation is the process where gas changes into a liquid state. Evaporation, on the contrary, is the conversion of a liquid to a gas. Therefore, the correct answer is B, deposition.
Which organ plays a significant role in immune cell production and maturation?
- A. Liver
- B. Kidneys
- C. Bone marrow
- D. Spleen
Correct Answer: C
Rationale: The bone marrow is the correct answer. It is the primary site for immune cell production and maturation. The bone marrow is responsible for generating various types of blood cells, including white blood cells crucial for the immune system's function. The liver, kidneys, and spleen have essential functions in the body, such as filtering blood, detoxification, and storage of blood, respectively. However, they are not primarily involved in immune cell production and maturation, making them incorrect choices for this question.
Deuterium, a stable isotope of hydrogen, has a nucleus containing:
- A. A single proton
- B. A proton and a neutron
- C. Two protons and an electron
- D. Two neutrons
Correct Answer: B
Rationale: Deuterium, as an isotope of hydrogen, has an atomic number of 1 and a mass number of 2. The nucleus of deuterium contains one proton (as in all hydrogen atoms) and one neutron, totaling 2 nucleons in the nucleus. Therefore, the correct answer is that deuterium's nucleus contains a proton and a neutron. Choices A, C, and D are incorrect. Deuterium is not just a single proton (A), doesn't have two protons and an electron (C), and doesn't contain two neutrons (D). The correct composition of deuterium's nucleus is one proton and one neutron.
What is the scientific term for the windpipe, a tube that carries air from the larynx to the bronchi?
- A. Pharynx
- B. Trachea
- C. Epiglottis
- D. Bronchiole
Correct Answer: B
Rationale: The trachea is the correct scientific term for the windpipe, a tube that carries air from the larynx to the bronchi. It is an essential part of the respiratory system, enabling the passage of air to and from the lungs. The pharynx is the region behind the mouth and nasal cavity, acting as a passageway for air and food. The epiglottis is a cartilage flap that shields the trachea during swallowing to prevent food from entering the airway. Bronchioles are smaller airways that branch off from the bronchi within the lungs, further dividing and distributing air within the lungs.