Brainlies ! which of the following correctly describes a mixture? the particles are chemically bonded together, and they retain their individual physical and chemical properties. the particles are not chemically bonded, and they can only combine in certain set ratios. the particles do not retain their individual chemical properties, and they can only be separated by chemical means. the particles have no set ratio for how to combine, and they can be separated by physical means.

Option (b) is the correct answer.

Explanation:

A mixture is a substance that contains two or more components mixed together in varying composition.

Components of a mixture never combine chemically with each other and hence, the components of mixture retain their individual properties.

For example, mud in water is a mixture.

Therefore, we can conclude that the statement, particles are not chemically bonded, and they can only combine in certain set ratios, correctly describes a mixture.

The option which correctly describes a mixture is: D. The particles have no set ratio for how to combine, and they can be separated by physical means.

A mixture can be defined as a combination of two (2) or more substances which are present in varied proportion (unfixed ratios). Also, a mixture can be visibly seen with our naked eyes and separated by physical means.

In Chemistry, there are two (2) main types of mixture and these are;

From the above definition of a mixture, we can deduce that the particles of a mixture have no set ratio for how to combine and they can be separated through the use of a physical separation technique.

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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 answer is b. dilution