Question

How many moles of HCl are required to completely neutralize 0.30 moles of Ca(OH)2?

Answer 1

0.60 you need 2moles HCl for 1mole Ca(OH)2 so 0.60

Answer 2

Each mole of Ca(OH)₂ will produce 2 moles of OH- ions

Each mole of OH- ions will require one mole of H+ ions

Thus,
moles of OH- ions = moles of H+ ions = 2 x 0.3
moles of H+ ions required = 0.6

Each mole of HCl will produce one mole of H+ ions
Moles of HCl = moles of H+ ions
Moles of HCl = 0.6