How many atoms are present in a 1.01g sample of Phosphorus (P)? [Note: 1 mol = 6.022x10²³ atoms, molar mass of Phosphorus =30.97 g/mol) * 1 point
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3.48 x 10²¹ atoms
1.97 x 10²² atoms
1.04 x 10²⁶ atoms
3.36 x 10²⁴ atoms

Explanation:

First, convert the grams to moles, then convert moles to atoms.

1. Grams to moles

To convert from grams to moles, we use the molar mass. Phosphorus's molar mass is given to use.

We can use this number as a fraction.

Multiply by the given number of grams (1.01)

Flip the fraction so the grams of phosphorus cancel out.

2. Convert Moles to Atoms

To convert from moles to atoms, we use Avogadro's Number.

This tells us the number of particles in 1 mole. In this case, it is atoms of phosphorus in 1 mole of phosphorus. We can create a fraction.

Multiply by the number of moles we calculated.

The moles of phosporus will cancel.

This is closest to 1.97*10²² atoms, so choice B is correct.

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.