What might you expect to observe from this double-displacement reaction: cocl2(aq) + na2so4(aq) > coso4 + 2nacl? edit a. coso4 precipitate will form. b. nacl precipitate will form. c. one of these products will bubble out as a gas. d. there will be no chemical change because there will be no chemical reaction; the ions will remain suspended in the water solution.

To decide the outcome of this reaction, we need to know the state of the products, as in if they are solid, liquid, gaseous, aqueous, etc. The proper reaction is as follows:

CoCl₂ (aq) + Na₂SO₄ (aq) → CoSO₄ (aq) + 2NaCl (aq)

If we were to look up the species CoSO₄ and NaCl, we would find that both of these species are also aqueous. Therefore, neither CoSO₄ or NaCl will precipitate from the solution, so we can ignore options A and B. Neither species formed is gaseous either, therefore, it cannot be option C. That leaves us with option D as the answer.

D is the correct answer because the product of the double displacement is the formation of two more aqueous species which will remain dissociated in the aqueous solution leading to no chemical reaction overall.

Answer: abeexplanation:

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 density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water