| A) -4 | B) -3 | 
| C) +4 | D) +2 | 
Explanation:
The given compound is NaHCO3 Sodium bicarbonate which is commonly known as Baking soda.
Oxidation numbers are the charges on ions. When a neutral atom loses electrons it becomes positively charged. When a neutral atom gains electrons it becomes negatively charged.
Here the C represents the oxidation state of carbon in this compound. Compounds are electrically neutral, which is why we set the sum of the oxidation states equal to zero.
Sodium has a +1 oxidation state. Hydrogen has a +1 oxidation state. Oxygen has a -2 oxidation state. There are three oxygen atoms, which means the total oxidation state provided by both oxygen ions is -6. Adding up these oxidation states we get:
1 + 1 + (-6) + C = 0
-4 + C = 0
=> C = 4
This means the oxidation state of carbon in this compound is +4.
 
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