Determine the mass of NaOH needed to make 750.0mL of a 6.00 M solution of NaOH

180g

Explanation:

No of moles= volume ×molarity/1000

Volume is given as 750ml

Molarity is given as 6M

Substitute to get the mole

No of moles = 750×6/1000

No of moles= 4.5moles

Remember that

No of moles also = mass given/molar mass

Molar mass of NaOH

Na= 23

O=16

H=1

Molar mass = na +o+h

Molar mass =23+16+1

Molar mass=40g/mol

Substitute

No of moles = mass given/molar mass

Mass = 4.5×40

Mass = 180g

The mass of NaOH needed is 180g

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 by yourhope:

how do models compare to real-world objects?

d. most models represent a real-world object in a simpler way.

: )