What are the bond enthalpies and bond lengths between carbon and carbon atoms in alkanes and alkenes?

An organic compound $C_4H_6$ on ozonolysis gives $HCHO$,$CO_2$,and $CH_3CHO$. The compound will be:

Give distinguishing tests for the following:
$(a)$ Ethane and ethyne (Alkane and Alkyne $RC \equiv CH$)
$(b)$ Ethene and Ethyne (Alkene and Alkyne $RC \equiv CH$)
$(c)$ Dimethyl ethyne and ethyne
$(d)$ Ethane and Ethene (Alkane and alkene)

The product of the reaction shown is:

Arrange benzene,$n-$hexane and ethyne in decreasing order of acidic behaviour. Also give reason for this behaviour.

The compound with molecular formula $C_6H_6$,which gives only one monobromo derivative and takes up four moles of hydrogen per mole for complete hydrogenation,has $................\pi$ electrons.