Answer:
An atom consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. The positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral.
<em>m Na₂CO₃: 23g×2 + 12g + 16g×3 = 106 g/mol</em>
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1 mol ------- 106g
X ------------ 10,6g
X = 10,6/106
<u>X = 0,1 mol Na₂CO₃</u>
An anion is an ion with a negative charge. The minus sign, when attached to the end of an ionic compound, indicates that this has a negative charge, while a plus sign indicates a positive charge.
O2- is the only compound listed that satisfied this. It is the anion.
Answer is 02-