In n-butane fully eclipsed conformation has highest energy due to presence of interaction between

Eclipsed from of ethane has higher energy due to

The fully eclipsed conformation of n-butane is least stable due to the presence of

The eclipsed and staggered conformation of ethane is due to -

Which of the following conformation has maximum energy ?

Does the eclipsed conformation of propane has same energy or different as eclipsed conformation of ethane?

Which has the highest bond energy?