There is 1 H atom: (1)(+1) = +1 The oxidation number of O is -2. There are 4 O atoms here: (4)(-2) = -8 So the oxidation state of Cl is +7.
NOTE: The maximum positive oxidation number for chlorine is +7,<span> the same as its group number (VII).</span>
Given the volume of HCl solution = 30.00 mL
Molarity of HCl solution = 0.1000 M
Molarity, moles and volume are related by the equation:
Molarity = 
Converting volume of HCl from mL to L:

Calculating moles of HCl from volume in L and molarity:

The final moles would be reported to 4 sig figs. So the correct answer will be 0.03000 mol HCl
Correct option: C. 0.03000mol
D ................................
Well, I know one. A positive: decreasing pollution because most people are in quarantine and not outside.