0.100 mole NaCl is dissolved into 100.0 g H2O. What is the mole fraction of NaCl?
how do i do this steps pls

Mole fraction NaCl  = 0.017

Explanation:

In order to determine the moles fraction we need to determine the moles of each, solute and solvent

Solute = NaCl

Solvent = Water

Moles of solute = 0.1 moles

Moles of solvent = 100 g . 1 mol/ 18g = 5.55 moles

Mole fraction of solute = Moles of solute / Total moles

Total moles = moles of solute + moles of solvent

Total moles = 0.1 + 5.55 = 5.65 moles

Mole fraction NaCl = 0.1 / 5.65 = 0.017

Mol fraction NaCl =  0.0177

Explanation:

Step 1: Data given

Number of moles NaCl = 0.100 moles

Mass H2O = 100.0 grams

Molar mass H2O = 18.02 g/mol

Step 2: Calculate moles H2O

Moles H2O = mass H2O / molar mass H2O

Moles H2O = 100.0 grams / 18.02 g/mol

Moles H2O = 5.549 moles

Step 3: Calculate total moles

Total moles = 0.100 moles + 5.549 moles

Total moles = 5.649 moles

Step 4: Calculate mol fraction of NaCl

Mol fraction NaCl = moles NaCl /total moles

Mol fraction NaCl = 0.100 moles / 5.649 moles

Mol fraction NaCl =  0.0177

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.

3 1/4 %

explanation: