Nokea
What type of reaction is represented by the following equation: 2C₆Hâ‚â‚„ + 19Oâ‚‚ → 12CO + 14Hâ‚‚O?
- A. Substitution reaction
- B. Acid-base reaction
- C. Enzyme reaction
- D. Combustion reaction
Correct Answer: D
Rationale: The given chemical equation represents a combustion reaction. Combustion reactions involve the burning of a hydrocarbon (C₆Hâ‚â‚„) in the presence of oxygen (Oâ‚‚) to produce carbon monoxide (CO) and water (Hâ‚‚O). Combustion reactions typically release heat and light energy. In this case, the reactants are a hydrocarbon and oxygen, resulting in the formation of carbon monoxide and water. Choices A, B, and C are incorrect because the reaction does not involve substitution, acid-base reactions, or enzyme catalysis. Combustion reactions are characterized by the rapid combination of a substance with oxygen, leading to the production of heat and light energy.
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Which of the following correctly describes a strong acid?
- A. A strong acid completely ionizes in water.
- B. A strong acid donates more than one proton.
- C. A strong acid contains at least one metal atom.
- D. A strong acid will not decompose.
Correct Answer: A
Rationale: The correct answer is A. A strong acid is defined as an acid that completely ionizes in water, meaning it dissociates fully into its constituent ions in solution. This characteristic differentiates strong acids from weak acids, which do not fully dissociate in water. Choice B is incorrect because the number of protons donated does not solely define the strength of an acid. Choice C is incorrect as strong acids are not defined by the presence of metal atoms, and Choice D is incorrect because all acids can decompose, but the strength of the acid is based on its ability to ionize in water.
Which of the following layers of skin acts as an energy reserve by storing adipocytes and releasing them into circulation when energy is needed?
- A. epidermis
- B. dermis
- C. hypodermis
- D. stratum basale
Correct Answer: C
Rationale: The hypodermis, also known as the subcutaneous tissue, is the deepest layer of the skin. This layer contains adipocytes (fat cells) that act as an energy reserve by storing excess energy in the form of fat. When energy is needed, these stored fats can be released into circulation to be used by the body's cells. The epidermis is the outermost layer of the skin, primarily responsible for providing a protective barrier. The dermis lies between the epidermis and hypodermis and contains blood vessels, nerves, and structures like hair follicles and sweat glands. The stratum basale is the deepest layer of the epidermis, responsible for cell renewal and regeneration.
Where is the pineal gland located in the body?
- A. Below the larynx
- B. Above the kidney
- C. At the center of the brain hemispheres
- D. At the base of the brain
Correct Answer: C
Rationale: The pineal gland is correctly located at the center of the brain, between the two hemispheres. It is a small endocrine gland often referred to as the 'third eye' due to its unique location. Choices A, B, and D are incorrect as the pineal gland is not situated below the larynx, above the kidney, or at the base of the brain.
Which of the following is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air?
- A. epiglottis
- B. bronchioles
- C. epithelium
- D. tongue
Correct Answer: A
Rationale: The epiglottis is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air. When we swallow, the epiglottis covers the entrance to the larynx, preventing food or liquid from entering the airway and instead directing them towards the esophagus for digestion. Choice B, bronchioles, are small airway branches within the lungs and are not involved in protecting the larynx from food or water. Choice C, epithelium, refers to the tissue that lines the surfaces of organs and structures in the body, but it is not the specific structure that protects the larynx as described. Choice D, tongue, plays a role in taste, speech, and swallowing, but it is not the cartilaginous flap that protects the larynx.
Which of the following chambers of the heart receives blood returning from the lungs during pulmonary circulation?
- A. left atrium
- B. right atrium
- C. left ventricle
- D. right ventricle
Correct Answer: A
Rationale: The correct answer is A, the left atrium. During pulmonary circulation, oxygenated blood returns from the lungs to the heart and enters the left atrium through the pulmonary veins. The left atrium then contracts, pushing this oxygen-rich blood into the left ventricle. The left ventricle subsequently pumps this oxygenated blood out to the rest of the body through the aorta. Choices B, C, and D are incorrect because the right atrium receives deoxygenated blood from the body, the left ventricle receives oxygenated blood from the left atrium, and the right ventricle pumps deoxygenated blood to the lungs for oxygenation, respectively.