<u>Answer:</u> The number of molecules of ethinyl estradiol present in one pill are 
<u>Explanation:</u>
To calculate the number of moles, we use the equation:

Given mass of ethinyl estradiol = 0.038 mg =
(Conversion factor: 1 g = 1000 mg)
Molar mass of ethinyl estradiol ![(C_{20}H_{24}O_2)=[(20\times 12)+(24\times 1)+(2\times 16)]=296g/mol](https://tex.z-dn.net/?f=%28C_%7B20%7DH_%7B24%7DO_2%29%3D%5B%2820%5Ctimes%2012%29%2B%2824%5Ctimes%201%29%2B%282%5Ctimes%2016%29%5D%3D296g%2Fmol)
Putting values in above equation, we get:

According to mole concept:
1 mole of a compound contains
number of molecules
So,
of ethinyl estradiol will contain =
number of molecules
Hence, the number of molecules of ethinyl estradiol present in one pill are 