Question

What is the oxidation state of H in PH₃?

Answer 1

Non metal hydrides (PH3 is non metal hydride): means Non metal will be in negative oxidation state being more electronegative. Here H has +1 state.

OR

Thus in case of PH3 the O.S. of hydrogen is +1 and O.S. of P is -3. Generally non metals are more electronegative than hydrogen. You have to understand one thing first, Hydrogen has a oxidation state of (-1) only when it reacts with a metal to create a metal hydride.

OR

Here's the answer you are looking for

Let us assume that the oxidation number of H is x.

Note:
♦The oxidation number of a molecule or compound is always zero.

♦The oxidation number of P is -3.

So now let's find out the value of x in PH3

Here,
-3 + 3X = 0

3X - 3= 0

X = 1

So in PH3 the oxidation number of H is +1