In which of the following compounds does nitrogen have +5 charge?
For a neutral molecule, all of the oxidation numbers must add up to zero. Also, we need to remember that generally oxygen has a -2 charge, and hydrogen has a +1 charge (group 1=+1, group2 = +2, group 16= -2, group =-1, with some exceptions).
Lets look at the first choice. In order to figure things out, we can make a simple equation where the oxidation number for nitrogen is x. Therefore, for HNO3, we get +1+x+(-2*3)=0 where +1 is the oxidation number of hydrogen, -2 is the oxidation number of oxygen and 3 is the number of oxygens in the molecule
x-5=0, thus x=5. This must be the correct answer choice. A
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