In 1 mol of CH3OH, you have 4 H-atoms (because 3 H-atoms
are attached to the C-atom, and one H-atom in the OH group). That means
in 0.500 mol of CH3OH, you have 2 H-atoms since it is halved. And then we have Avogadro's constant: 6.02 * 1023.
The question asks for how many hydrogen atoms there are in 0.500 mol CH3OH. Using the numbers that we have (Avogadro's constant and no. of H-atoms), the answer of the question will be something like:
<span>H-atoms in CH3OH = 2 * 6.02 * </span>1023<span> = ~1.2 * 10</span>24
The correct answer would be 10:)
The reaction equation is Mg(OH)2 + 2HCl = MgCl2 + H2O. The mol number of Mg(OH)2 is 2.96/58=0.051 mol. So we need 0.051*2=0.102 mol HCl to neutralize. The volume is 0.102/0.126=0.810 L =810 mL.