Which quantity expresses the sum (2.1 g + 33.566 g + 12.22 g) to the proper degree of precision

First let us get the sum of the numbers.

2.1 g + 33.566 g + 12.22 g = 47.886 g

Now to get the proper degree of precision, the amount of decimal places should be equal to the least decimal places of the numbers that were added. In this case, 2.1 g has the least number of decimal places which is equal to 1, hence the correct answer is:

47.9 g

some sources quote the lethal dose, for an average 170lbs opiate-naive individual is between 75 and 375 mg

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

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~ trueboss72