Cc28417 avatar cc28417
15 minutes ago
Chemistry
Middle School
answered
Please help!
Samira watched a demonstration in which a scientist combined two substances in a sealed container and analyzed the results. The ending substances did not look the same as the starting substances.

Samira was given a diagram with the repeating groups of atoms that make up the starting substances, plus information about the properties of the starting and ending substances. She created a model of the repeating groups of atoms that might make up the two ending substances.

A.) Does her model correctly show why the properties of the ending substances are different from the properties of the starting substances?

B.) Describe what could be correct or incorrect about her model

Look at the diagram below then write your answer to question 13 part "A" and "B".
THIS IS NOT A MULTIPLE CHOICE QUESTIONS YOU NEED TO ANSWER BOTH QUESTIONS
thanks

Explanation:

i don't know the answer so if you don't mind can you help me ?

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.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.