How much stock solution is needed to make 250 mL of a 6.0 M solution. The stock solution has a molarity of 18 M.

83 mL

Explanation:

Use the dilution equation M1V1 = M2V2

M1 = 18 M

V1 = ?

M2 = 6.0 M

M2 = 250 mL

Solve for V1 --> V1 = M2V2/M1

V1 = (6.0 M)(250 mL) / (18 M) = 83 mL

air quality

poor drinking water

and heavy polution

can lead to poor health

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