Which compound has the longest carbon-carbon bond length? which compound has the longest carbon-carbon bond length? hcch ch3ch3 ch2ch2 all bond lengths are the same?

Each carbon atom is capable of bonding to 4 elements. So, 

HCCH is CH≡CH
CH₃CH₃ is CH₃ - CH₃
CH₂CH₂ is CH₂ = CH₂

The longest bond length is always the triple bond, then the double bond, and the shortest bond is the single bond. Therefore, the compound with the longest C-C bond is HCCH or CH≡CH.

Well to my expert knowledge and my exquisite calculations i think the the negative ion # 412 is the key to sucess

Hno3(aq) → h+(aq) + no3−(aq). picture ii best represents the strong acid hno3. strong acids are strong electrolytes