Polymerisation of Alkenes

Q. Propyne on polymerisation gives

1. Mesitylene
2. Benzene
3. Ethyl benzene
4. Propyl benzene

Q. When ethene is heated at ${400}^{\circ }C$ under high pressure, the product is/are

1. Carbon and $H_2$
2. Polyethylene
3. Acetylene and $H_2$
4. None of these