A concave mirror of focal length 20 cm forms an image twice the size of the object. For the virtual position of the object, the position of the object will be at:
(a) 25 cm
(b) 40 cm
(c) -10 cm
(d) At infinity

b is the correct

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