Answer:
B, C
Explanation:
The Lewis dot structures that are valid are for B and C.
Regarding A;
The Lewis representation of carbon is correct. Each of the four dots symbolizes the four valence electrons.
However, the nitrogen with a single dot above, to the left, and below and a -3 charge isincorrect. For it to have a -3 charge, it must possess 8 Lewis dots (two on each side).
The nitrogen showing four dots (on top, right, bottom and left) is incorrect.
In B;
An oxygen having two dots positioned above and below with one dot on both sides is correct , as the 6 dots indicate oxygen's valence electrons.
In C;
A carbon shows two dots at each position and has a charge of +4. This is correct because the charge reflects that it has gained four electrons giving it 8 valence electrons.
In D;
An oxygen shows two dots above, to the left and below, with a charge of -2. This is incorrect as not all Lewis dots are present. Two are missing.