The level of a liquid (i. e. distilled water) in laboratory glassware is determined by sight. The level corresponds to a specific volume. The volume is established by identifying the meniscus of the liquid relative to a calibration mark or series of calibration marks on the glassware (ie. volumetric flask vs. buret). Which of the following statements is NOT correct when reading the meniscus? a. The edge of the meniscus should be used to determine volume relative to the mark or marks
b. The meniscus should be read at eye level
c. When the meniscus is between marks, estimate the reading to the nearest tenth of a division (ie, estimate to 0.01 mL if buret has 0.1 ml divisions)
d. The center of the meniscus should be used to determine volume relative to the mark or marks

c. When the meniscus is between marks, estimate the reading to the nearest tenth of a division (ie, estimate to 0.01 mL if buret has 0.1 ml divisions)

Explanation:

The meniscus is the mark that a liquid presents in a pipette. This measure is important for determining the volume of a solution, allowing the correct amounts of aqueous solutions to be used. The meniscus must be observed at eye level to avoid parallax errors. In this view, the border and center of the meniscus must be considered to determine the volume.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.