Not sure about the last one, but I think the percent composition of zinc would be ~ 42.8232
There are O-H bonds in H2O. They have the intramolecular force of polar covalent bond.
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Mole ratio for the reaction is 1:1
no of moles in NaOH that reacted= 1*21.17/1000=0.02117mols
molarity of HCl=0.02117*10/1000
=2.117M