Iron(III) sulfide reacts with hydrochloric acid to produce hydrogen sulfide and iron(II) chloride. Wright the formula equation for this reaction and balance it.

Fe2S3 + 4HCl —> 2H2S + 2FeCl2 + S

Explanation:

From the question, we were told that:

Iron(III) sulfide reacts with hydrochloric acid to produce hydrogen sulfide and iron(II) chloride.

Please note that elemental sulphur is produced along with this reaction. The equation for the reaction is given below:

Fe2S3 + HCl —> H2S + FeCl2 + S

Now, we can balance the equation as shown below:

There are 3 atoms of S on the left side of the equation and 2 atoms on the right. It can be balance by putting 2 in front of H2S as shown below:

Fe2S3 + HCl —> 2H2S + FeCl2 + S

Now, we have 4 atoms of H on the right side and 1atom on the left side. It can be balance by putting 4 in front of HCl as shown below:

Fe2S3 + 4HCl —> 2H2S + FeCl2 + S

Also, there are 4 atoms of Cl on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of FeCl2 as shown below:

Fe2S3 + 4HCl —> 2H2S + 2FeCl2 + S

Now, we can see that the equation is balanced

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.