A new method of determining cobalt in soil sample gave 99.35% recovery (variance 0.185). the standard method gave 99.53% recovery (variance 0.152). In each case three

replicate measurements were made. Test whether the two means differ significantly at the

95% confidence level.​

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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