Hree carbon atoms are linked by single covalent bonds such that they form the shape of a v. all of the unshared electrons form covalent bonds with hydrogen. how many hydrogen atoms does this molecule contain?

Carbon atom having 4 valence electrons can form 4 covalent Bonds. As there are 3 carbon atoms in the molecule connected to each other by single bond. So the terminal carbons are left with 3 unbonded electrons and the central carbon is left with two unbonded electrons. So, terminal carbons will further form three single bonds with 3 hydrogen atoms each and the central carbon will form two covalent bonds with 2 hydrogen atoms, i.e. 

                                             H₃C-CH₂-CH₃

Result: 
          This Molecule contains 8 Hydrogen atoms.

D. is the answer hope that you