Iron reacts with oxygen to produce iron oxide rust this reaction is representative in an equation as to FE plus XO22FE203 identify the value of X that will balance this equation

The balanced equation :

4Fe + 3O₂⇒ 2Fe₂O₃

Given

Rust reaction

Required

Balanced equation

Solution

Reaction

Fe + O₂⇒ 2Fe₂O₃

For a simple equation where one of the reaction coefficients is known, we can immediately add the corresponding coefficient using the principle that the number of atoms of the components in the reactants and products is the same.

In the above reaction :

Fe, left=1, right = 4, so coefficient in the left=4

O, left=2, right = 6, so coefficient in the left=3

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.