Which is six member of alkyne series

Which is the first stable member of alkyne series and what is its common name?

Write structures of different isomers corresponding to the 5th member of alkyne series. Also write IUPAC names of all the isomers. What type of isomerism is exhibited by different pairs of isomers?

The first member of alkyne homologous series is

Solanaceae is a member of series

If the wavelength of the first member of Balmer series of hydrogen spectrum is 6564A^(@) , the wavelength of second member of Balmer series will be:

The Wavelength of first member of Balmer series in hydrogen spectrum is lambda . Calculate the wavelength of first member of Lymen series in the same spectrum