Hematite is a naturally occurring mineral and a common form of iron ore. the following statements describe physical and chemical changes occurring to hematite. which statement describes a chemical change? a. the hematite particles separate from each other but remain the same substance. b. the hematite particles rearrange to form a new substance. c. the hematite particles are mixed with particles of a different substance. d. the hematite particles vibrate more quickly when they are heated. e. the hematite particles are moved from one location to another location.

The correct answer is option B.

The hematite particles rearrange to form a new substance. This is an example of a chemical change.

A chemical change is an irreversible process wherein the atoms of a substance undergoes a rearrangement that causes it to from a new substance with  unique chemical properties.

B. The hematite particles rearrange to form a new substance.

Explanation:

PLATO

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.