1. division into two classes.   antiseptic   dichotomy   flora   correlation   Hint Half-n-half Clue   2. tooth of a wheel.   autopsy   cog   genesis   floe   Half-n-half Clue   3. botanical garden where trees are studied and exhibited.   arboretum   aperture   dichotomy   foliage   Half-n-half Clue   4. wasting away.   atrophy   diminution   degradation   conduit   Half-n-half Clue   5. state of being motionless.   immobility   gyroscope   imbalance   effervescence   Half-n-half Clue   6. exhalation affecting smell.   alchemy   effluvium   congruence   acoustics   Half-n-half Clue   7. unit for measuring weight of gems and purity of gold.   carat   chisel   delirium   chassis   Half-n-half Clue