Each clue below can be answered using variations of the same word:

1. It's negotiable

2. It's not negotialble

3. It's illegal

4. It's a reversal of a situation

5. It's chemical

6. It's mathematical

Answers:

The word is TABLE

1. On the table

2. Off the table

3. Under the table

4. Turn the tables

5. Periodic Table

6. Multiplication Table