In order to identify the molecular formula of that compound it would be better if we try to solve for the structure of the compound.

1. 7 octyne means that the triple bond is on the seventh carbon in the 8 carbon chain.

`-C-C-C-C-C-C-C-=C-`

2. 2,4 dimethyl means that there are two (2) methyl (-CH3) groups attached in the 2nd and 4th carbon in the octyne chain.

`-C-C(CH3)-C-C(CH3)-C-C-C-=C-`

3. 5 chloro means that the -Cl atom is attached in the 5th carbon in the octyne chain

`-C-C(CH3)-C-C(CH3)-C(Cl)-C-C-=C-`

4. Since it is an alcohol, we can add an -OH in the compound. However, the position of the -OH is not specified.

 `-C(OH)-C(CH3)-C-C(CH3)-C(Cl)-C-C-=C-`

4. Finally, supply all the remaining bonds with hydrogen (-H) following the octet rule.

`H_(2)C(OH)-CH(CH3)-CH_(2)-CH(CH3)-C(H)(Cl)-CH_(2)-C-=C-H`

We can now get the formula of this compound.

Answer: `C_(10)H_(17)ClO`