1. violent disturbance or agitation.   patina   precipitant   strut   turbulence   Hint Half-n-half Clue   2. residue from smelting operation.   residue   placebo   slag   parameter   Half-n-half Clue   3. discovery by accident.   serendipity   miasma   panacea   spectrum   Half-n-half Clue   4. smallest particle of a substance with all its properties.   vise   projectile   virus   molecule   Half-n-half Clue   5. layer of earth's crust or society.   whorl   stratum   spatula   quadruped   Half-n-half Clue   6. navigational instrument for angular measurements.   quagmire   magnitude   symbiosis   sextant   Half-n-half Clue   7. quantity that can be defined or that can limit.   parallelism   insomnia   symbiosis   parameter   Half-n-half Clue