NAMES

Which of the following molecules have some hindered rotation involved in their structures?  Draw the Lewis dot structure (if not present) and tell where the hindered rotation is or, if it is not present, explain why.

H2FCCH2F hindered?   yes   no why? __________________________	HFNNHF hindered?   yes   no why? __________________________
HFCCHF hindered?   yes   no why? __________________________	HNNH hindered?   yes   no why? __________________________
HCCH hindered?   yes   no why? __________________________	hindered?   yes   no why? __________________________