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What type of chemical bond connects the oxygen and hydrogen atoms in a molecule of water?
- A. Static bond
- B. Aquatic bond
- C. Ionic bond
- D. Covalent bond
Correct Answer: D
Rationale: The correct answer is D, Covalent bond. Covalent bonds are formed between oxygen and hydrogen atoms in a water molecule. In a water molecule, each hydrogen atom forms a covalent bond with the oxygen atom, sharing electrons to achieve a stable configuration. Static bond (choice A) and Aquatic bond (choice B) are not valid types of chemical bonds. Ionic bond (choice C) involves the transfer of electrons between atoms of different electronegativities, which is not the case between oxygen and hydrogen in a water molecule.
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Based on the following evidence, what is the most likely reason that spoiled food left out in the open often contains fly larvae?
- A. The spoiled food evolves into fly larvae.
- B. Since the food is left out in the open, flies lay eggs in the food.
- C. Fly larvae are spontaneously generated by the spoiled food.
- D. People only imagine they see fly larvae in the spoiled food.
Correct Answer: B
Rationale: The correct answer is B. Flies laying eggs in the food when it is left exposed to the air is a common occurrence and a logical explanation for the presence of fly larvae in spoiled food. Choice A is incorrect as food cannot evolve into fly larvae; fly larvae come from eggs laid by flies. Choice C is incorrect as fly larvae do not spontaneously generate from spoiled food but rather develop from eggs laid by flies. Choice D is incorrect as the presence of fly larvae in spoiled food is a real phenomenon, not merely imagined by people.
Which of the following statements describes a chemical property of water?
- A. Water has a pH of 1.
- B. A water molecule contains 2 hydrogen atoms and 1 oxygen atom.
- C. A water molecule contains 2 oxygen atoms and 1 hydrogen atom.
- D. The chemical formula for water is HO.
Correct Answer: B
Rationale: The correct answer is B because a water molecule consists of two hydrogen atoms and one oxygen atom, which is a fundamental chemical property of water. The pH of water is not a property of the water molecule itself but rather a measure of its acidity or alkalinity. Choice C is incorrect as it describes a different molecule, not water. Choice D provides an incorrect chemical formula for water, which is H2O.
Two nursing students will be completing a scientific experiment measuring the mass of chewed gum after one-minute chewing increments. Which lab equipment will the students most likely use?
- A. Triple beam balance
- B. Anemometer
- C. Hot plate
- D. Microscope
Correct Answer: A
Rationale: The correct answer is A: Triple beam balance. A triple beam balance is the most suitable lab equipment for measuring mass accurately, which is necessary for this experiment. An anemometer measures wind speed, a hot plate is used for heating substances, and a microscope is used for magnifying objects, none of which are relevant to measuring the mass of chewed gum.
Fill in the blanks in the following sentence: Enzymes are ________ molecules that serve as _______ for certain biological reactions.
- A. complex; suppressors
- B. acidic; triggers
- C. small; targets
- D. large; catalysts
Correct Answer: D
Rationale: Enzymes are large molecules that act as catalysts, accelerating chemical reactions by lowering the activation energy required for the reactions to occur. In the context of biological reactions, enzymes function as catalysts, not suppressors, triggers, or targets. The use of 'large' and 'catalysts' accurately describes the nature and role of enzymes in facilitating biological processes.
Which statement below correctly describes the movement of molecules in the body and in relation to the external environment?
- A. Osmosis is the movement of a solution from an area of low solute concentration to an area of high solute concentration.
- B. Diffusion is the process in which oxygen moves from the lungs into the bloodstream.
- C. Dissipation is the transport of molecules across a semipermeable membrane from low to high concentration.
- D. Reverse osmosis is the movement of molecules in a solution from high concentration to low concentration.
Correct Answer: B
Rationale: The correct answer is B. Diffusion is the process where molecules move from an area of higher concentration to an area of lower concentration. In the context of the lungs, oxygen moves from the alveoli in the lungs to the bloodstream through diffusion. Choice A is incorrect as osmosis involves the movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. Choice C is incorrect because dissipation does not refer to a specific biological process related to molecule movement. Choice D is incorrect as reverse osmosis is a process where solvent moves from an area of high solute concentration to an area of low solute concentration, not the movement of molecules within a solution.