1. Draw a six-carbon-chain portion from isotactic polypropylene, in which all of the groups point in the same direction, that is, either all behind or all in front of the plane of the computer screen. represents the continuation of the polymer chain. Do not add any bonds to X.
2. Draw a six-carbon-chain portion from syndiotactic polypropylene, in which the groups lie on alternating sides of the plane of the computer screen. represents the continuation of the polymer chain. Do not add any bonds to X.
3. Draw a six-carbon-chain portion from atactic polypropylene, in which the groups are randomly distributed on either side of the plane of the computer screen. represents the continuation of the polymer chain. Do not add any bonds to X.