A chemist prepares a solution of pottasium bromide KBr by measuring out 224.g of pottasium bromide into a 300.mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mo/L of the chemist's pottasium bromide solution. Round your answer to 3 significant digits.

The concentration of the KBr solution is 6.27 mol/L

Explanation:

Step 1: Data given

Mass of KBr = 224 grams

Molar mass KBr = 119.0 g/mol

Volume = 300 mL = 0.300 L

Step 2: Calculate moles KBr

Moles KBr = mass KBr / molar mass KBr

Moles KBr = 224 grams / 119.0 g/mol

Moles KBr = 1.88 moles

Step 3: Calculate concentration KBr solution

Concentration solution = moles KBr / volume

Concentration solution = 1.88 moles / 0.300 L

Concentration solution = 6.27 mol / L

The concentration of the KBr solution is 6.27 mol/L

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.

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.