Propane, c3hs. is flammable and used in rural areas where natural gas is not available. what is the coefficient of oxygen in the balanced equation for the combustion of propane? _c3 hp)* 026) > _co24) _h206) a) 1 b) 5 c) 10 d) 7 e) none of the above

The coefficient of oxygen in this balanced reaction is 5 ( option B)

Explanation:

Propane = C3H8

The process of combustion = adding oxygen (O2)

In this process propane will be consumed and CO2 and H2O will be produced.

C3H8 + O2 → CO2 + H2O

First we'll balance on both sides all H-atoms: left we have 8x H and on the right side we have 2x H so we have to multiply the right side ( H2O) by 4.

This gives us:

C3H8 + O2 → CO2 + 4H2O

Now we have on both side 8x H

On the left side we have 3x C, and 1x C on the right side. So we have to multiply CO2 on the right side by 3

This gives us: C3H8 + O2 → 3 CO2 + 4 H2O

On the left side we have 2x O but on the right side we have 10x O

We have to multiply O2 on the left side by 5, to equal this.

So finally, we'll have: C3H8 + 5 O2  → 3 CO2 + 4 H2O

We can see that the coefficient of oxygen in this balanced reaction is 5 ( option B)

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.

distance, luminosity, brightness, radius, chemical composition, and temperature