Oxygen has six valence electrons, and an electronegativity of 3.44. Calcium has two valence electrons and an electronegativity of 1.00. How can the octet rule be used to explain the bonding between them?

Oxygen needs to lose six electrons to reach a full octet. Each calcium atom needs access to six electrons to achieve a full octet. One oxygen atom donates all its electrons to calcium, forming an ionic bond.

Oxygen needs access to two electrons to reach a full octet. Each calcium atom has two valence electrons that it prefers to lose to obtain a full octet. Therefore, one oxygen atom and one calcium atom complement each other and form an ionic bond.

Oxygen needs access to two electrons to reach a full octet. Each calcium atom has two valence electrons that it prefers to lose to obtain a full octet. Therefore, one oxygen atom and one calcium atom complement each other and form a covalent bond.

Oxygen needs to lose six electrons to reach a full octet. Each calcium atom needs access to six electrons to achieve a full octet. One oxygen atom donates all its electrons to calcium, forming a covalent bond.

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.

yes

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