Which of the following is a characteristic of a chemical reaction?
Change in color
Formation of a precipitate
Release of gas
Change in temperature
All of the above
The Correct Answer is E
Choice A reason: A color change during a chemical reaction indicates the formation of new substances with altered molecular structures, affecting light absorption. For instance, iron reacting with oxygen forms iron oxide, shifting from silver to reddish-brown. This reflects a chemical transformation where new compounds with distinct optical properties are produced, confirming a reaction at the molecular level.
Choice B reason: Precipitate formation signifies a chemical reaction as soluble reactants produce an insoluble solid. In a double displacement reaction, such as silver nitrate combining with sodium chloride, silver chloride precipitates. This occurs due to ion exchange, forming a new compound with low solubility, providing visible evidence of a chemical change driven by molecular restructuring.
Choice C reason: Gas release during a reaction indicates a chemical change, as new gaseous products form from reactants. For example, sodium bicarbonate reacting with acetic acid produces carbon dioxide gas. This results from molecular bond rearrangement, where reactants break and reform into new molecules, including a gas, confirming a chemical transformation.
Choice D reason: Temperature changes often accompany chemical reactions, reflecting energy shifts. Exothermic reactions, like combustion, release heat, increasing temperature, while endothermic reactions absorb heat, decreasing it. These changes occur as chemical bonds break and form, redistributing energy. This energy dynamic is a hallmark of chemical reactions, indicating molecular-level transformations.
Choice E reason: This choice is correct as all listed signs—color change, precipitate formation, gas release, and temperature change—are indicators of chemical reactions. Each reflects molecular rearrangements, such as new compound formation or energy shifts. By encompassing all these observable phenomena, this option accurately represents the diverse physical manifestations of chemical changes.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A reason: Ankle circumference monitors edema, which mannitol reduces by drawing fluid from tissues. However, this is secondary to urinary output, as mannitol’s primary action is diuresis, increasing urine production to reduce intracranial or intraocular pressure, making edema measurement less critical.
Choice B reason: Heart rate is relevant for overall monitoring but not the primary outcome for mannitol, which acts as an osmotic diuretic. Cardiovascular effects are secondary, and mannitol’s efficacy is better assessed by urine output, which directly reflects its diuretic mechanism.
Choice C reason: Dietary intake is unrelated to mannitol’s therapeutic effect. Mannitol pulls fluid into the bloodstream, increasing urine output, not influenced by diet. Monitoring intake may be relevant for other conditions, but it is not critical for assessing mannitol’s diuretic action.
Choice D reason: Urinary output is the most important outcome, as mannitol, an osmotic diuretic, increases urine production by drawing fluid into the renal tubules, reducing intracranial or intraocular pressure. Adequate output (e.g., >30 mL/hour) confirms efficacy, preventing fluid overload or renal complications.
Correct Answer is A
Explanation
Choice A reason: Polyethylene glycol, a bowel prep for colonoscopy, requires rapid drinking at specified intervals to ensure effective colon cleansing. This osmotic laxative draws water into the bowel, promoting evacuation. Consistent, rapid intake ensures complete bowel clearance, critical for clear visualization during the procedure.
Choice B reason: Diluting polyethylene glycol with fruit juice is incorrect, as it may alter the solution’s osmotic balance, reducing efficacy. The preparation must remain undiluted to draw sufficient water into the colon for cleansing, making this instruction inappropriate for achieving a clear colonoscopy.
Choice C reason: Drinking polyethylene glycol with a meal is incorrect, as food can interfere with bowel cleansing. The solution is taken on an empty stomach, typically the day before the exam, to ensure the colon is clear, making this instruction counterproductive to the prep’s purpose.
Choice D reason: Watery diarrhea is the expected outcome of polyethylene glycol, not an adverse effect requiring reporting. It indicates effective bowel cleansing for colonoscopy. Instructing to report this normal response is unnecessary and may cause confusion, as diarrhea is the goal of the preparation.
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