Mumbai, July 31 -- COMEX copper collapsed by over 20%, suffering its largest intra-day fall on record after President Donald Trump announced exemption of the most widely imported form of copper from his planned tariffs. Sentiment was also dented as Trump announced a narrower-than-expected 50% tariff on copper pipes and wiring. The red metal is currently quoting at $4.44 per pound, down 20.52% on the day following a sharp slump in the previous session from around record high levels. Meanwhile, choppy show in overnight equities also failed to provide any support to the counter. While the tech-heavy Nasdaq rose 31.38 points or 0.2 percent to 21,129.67, the S&P 500 edged down 7.96 points or 0.1 percent to 6,362.90 and the Dow fell 171.71 points...