1. echo or reflect sound, light or heat.   reverberate   integrate   regenerate   manipulate   Hint Half-n-half Clue   2. multiply and spread.   propagate   incorporate   weather   implement   Half-n-half Clue   3. burst inwards.   sap   invalidate   implode   splice   Half-n-half Clue   4. melt ores for extraction of metal.   smelt   purge   splice   perforate   Half-n-half Clue   5. put into effect.   secrete   manipulate   precipitate   implement   Half-n-half Clue   6. crush to powder or dust; demolish.   pulverize   propagate   masticate   secrete   Half-n-half Clue   7. lay down as basis or truth.   manipulate   regenerate   oscillate   postulate   Half-n-half Clue