Which of the following is recommended for extinguishing or controlling the spread of alkali metal fires

Explanation:

The answer choices for this question are:

Alkali metals, like lithium, sodium and potassium, react violently with water, and must be kept in a dry atmosphere to avoid explosion and fire.

There is a specific norm from the National Fire Protection Association, Inc, named NFPA 484 Standard for Combustible Metals, Metal Powders, and Metal Dusts and a chapter for LIthium where it states the use of Class  D  extinguishing  agents.

Class D fire extinguisher is Dry Powder extinguisher.

Carbon dioxide is not suitable for extinguishing or controlling the spread of alkali metal fires because they can react and increase the fire or spread the metal dust.

Oxygen, of course, is not a fire extinguisher agent, on the contrary it is a essential component of fire: the ost basic principle to extinguish fires is to to remove the oxygen around the fire.

what is the volume occupied by 40 grams of argon gas (ar) at standard conditions? what volume, in liters, is occupied by 1.5 x 1023 

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.