Using what you know about intermolecular forces, determine which of the following molecules has the highest boiling point. using what you know about intermolecular forces, determine which of the following molecules has the highest boiling point. hf ch4 ph3 hcl

HF will have the highest boiling point

Explanation:

CH4 is non-polar hence contain only weak van der waals forces hence it will have a low boiling point. HCl will have a lower boiling point than HF since F is more electronegative than Cl and possess a greater degree of hydrogen bonding. P is much less electronegative than both Cl and F hence PH3 has a much less degree of hydrogen bonding. Hydrogen bonding exists between hydrogen and a weakly electronegative atom.

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.

the answer is c.the valence of the atoms combine .