Polymerisation of Alkynes

Q. A compound P having a molecular formula $C_3{H}_4$ answers positively to Tollens' test. When the same compound P is passed through a red hot iron tube, it gives product Q.

If the DBE of Q is X and the molecular mass of Q is Y, then $\frac{Y}{X}$ is .

Q. Polymerisation product of propyne is

1. Benzene
2. Ethylbenzene
3. 
   Propylbenzene
4. 1, 3, 5-trimethylbenzene