The general formula for the alkyne series is: cnh2n+2 cnh2n cnh2n-2 cnhn+2

The general  formula  for  alkyne  series  is     CnH2n-2

 This is because alkyne  is unsaturated  hydrocarbon   which has  one  triple  bond   and   has  no functional  group  from   homologous series. Alkyne  has  a  general formula of  CnH2n-2

An  example  of an  alkyne  in  ethyne    with HC≡CH  chemical formula ,

another example is propyne   with  CH3C≡CH  formula

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.