Part a) theobromine, c7h8n4o2, is a component of chocolate. it is mildly diuretic, is a mild stimulant, and relaxes the smooth muscles of the bronchi in the lungs. because dogs metabolize it more slowly than humans, theobromine is very toxic to dogs.
if there are 0.064 g of theobromine in a 43 g chocolate bar, how many moles of theobromine are there?
a) 1.5 x 10−3 moles
b) 3.55181 x 10−4 moles
c) 3.6 x 10−4 moles
d) 12 moles
part b) calculate the molarity (m) of 151.1 g of h2so4 in 1.405 l of solution.
express your answer to four significant figures.
part c) sodium hydroxide, naoh, is a strong base that is used in industrial synthesis and processes such as making paper.
what is the mass of 2.30 ×1022 molecules of naoh (molar mass = 40.0 g/mol)?
express the mass in grams to three significant figures.

a. 3,6x10⁻⁴ moles

b. 1,096M

c. 1,53 g of NaOH

Explanation:

a. Theobromine has a molar mass of:

C: 12,01×7= 84,07 g/mol

H: 1,01×8= 8,08 g/mol

N: 14×4= 56,04 g/mol

O: 16×2= 32 g/mol

84,07 g/mol + 8,08 g/mol + 56 g/mol + 32 g/mol = 180,15g/mol. Thus, in 0,064g of theobromine are:

= 3,6x10⁻⁴ moles -two significant figures-

b. Molar mass of H₂SO₄ is 98,079 g/mol.

151,1g are:

= 1,54 moles of H₂SO₄

As molarity is moles of solute per liters of solution, molarity is:

1,54 moles of H₂SO₄ / 1,405L = 1,096 M

c. 2,30x10²² molecules of NaOH are:

2,30x10²²molecules × (1mol/6,022x10²³molecules) = 0,0382 moles of NaOH

As molar mass of NaOH is 40,04g/mol:

= 1,53 g of NaOH

I hope it helps!

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.