1- Calcule a concentração comum de uma solução que apresenta volume de 800 ml e contem 20g de soluto. 2- São dissolvidos 400g de cloreto de sódio em água suficiente para 2L de solução. Qual é a concentração comum dessa solução?
3- A concentração comum de uma solução é de 20g/L. Determine o volume dessa solução, sabendo que ela contém 75g de soluto.
4- Calcule a concentração em mol/L de uma solução que foi preparada dissolvendo-se 18 gramas de glicose em água suficientes para produzir 1 litro de solução. (Dado: massa molar da glicose = 180 g/mol)
5- No preparo de uma solução aquosa, foi usado 0,4g de cloreto de sódio como soluto. Sabendo que a concentração da solução resultante é de 0,05 mol/L, determine o volume final. Dados: M molar do cloreto de sódio = 58,5g/mol
6- Qual o nº de mols de ácido sulfúrico (H2SO4) será necessária para preparar 2 Litros de uma solução na concentração de 3 mol/L? Dado: M(H2SO4) = 98g/mol.

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.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).

the formula for the conversion of temperature from degree celsius to kelvin is:

the sample of water at is converted to kelvin temperature by using the above formula as:

on comparing the two samples of water at or we can say that at and at respectively. the difference between the temperatures of two samples of water is:

hence, one can say that the sample of water at is greater than the sample of water at by .