- "Record the temperature every 5 minutes. If it goes above 40 degrees C, remove the lamp at once." At minute 15 it reads 42. What should you do?
Answer: Remove the lamp right away
42 is above 40, and the procedure says to remove the lamp "at once," so it should come off immediately. Waiting for the next reading is tempting because of the 5-minute schedule, but the warning overrides that routine.
- "Do not skip the cooling step; warm glass can crack when cold water touches it." The writer most likely expects readers to
Answer: be tempted to skip cooling to save time
A direct warning against skipping a step shows that the writer expects readers to want to rush past it. Readers who already knew why glass cracks would not need the explanation the writer includes, so that choice does not fit.
- What is the purpose of this lab step? "Zero the scale, set the empty cup on it, and press tare again before adding soil."
Answer: Measure only the soil by zeroing out the cup's mass
Pressing tare with the empty cup on the scale sets the reading back to zero, so the scale then shows only the soil's mass. Weighing cup and soil together is tempting, but taring is done to remove the cup from the measurement.
- "Let the sediment settle for two minutes, then decant the clear water into a second jar." As used here, "decant" most nearly means
Answer: pour off gently, leaving the solids behind
The sediment settles first and only the clear water is moved, so decant means to pour off liquid gently and leave the solids behind. Straining through a filter also separates solids, but the step describes pouring, not filtering.
