3SCS #1, 3, 6, 13 p.279, 3SBS #11 and 12, p.258

1. A. 1 repeating unit
    B. 2 repeating units
    C. 3 repeating units
    D. 500-20,000 or more repeating units

3. Natural polymers: medicines, food additives, cotton, and silk
    Synthetic polymers: celluloid, shellac, nylon, plastic toys

6. The term unsaturated is used to describe the structures of alkenes and alkynes because not all carbon atoms are bonded to their full capacity with four other atoms.

13.

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11. A. ii
      B. iii
      C. i
      D. ii

12. The other 75% is lost in heat, and this is why the engine is so inefficient.