When you use exponents, think of it like this. 1 squared is 1 x 1. 1 cubed is 1 x 1 x 1. And 1 to the power of 4 is 1 x 1 x 1 x 1. And so on. You basically just multiply them by themselves. 0 to the power of any exponent is 1, well that's just a rule. It doesn't make much sense but it's easy to remember and I wouldn't worry about it.
<u>Answer:</u> The amount of white phosphorus is 0.0199 moles
<u>Explanation:</u>
To calculate the number of moles, we use the equation:

We are given:
Given mass of white phosphorus = 2.478 g
Molar mass of white phosphorus = 124 g/mol
Putting values in above equation, we get:

Hence, the amount of white phosphorus is 0.0199 moles