00:02
Hello.
00:04
In this question, we have hydrozine, which has the formula n2h4.
00:12
And we want to know the oxidation number of nitrogen.
00:16
So to answer this, we need to know two of the rules for assigning oxidation numbers.
00:20
The first rule is that in a neutral compound, such as this, the sum of the oxidation numbers is zero.
00:41
All right.
00:42
And the other rule that we need to know is that hydrogen, except, when it is in a metal halide, hydrogen, or a metal hydride, rather, i'm sorry, except when it's in a metal hydride, hydrogen has an oxidation number of positive one.
01:12
Okay, so our hydrogen here has an oxidation number of positive one, and there are four hydrogens.
01:18
So four times that positive one, when added to two times whatever the oxidation number is of the nitrogen, has to add up to zero...