It has been possible to raise the yield of resin from chir pine from the existing 1.5 kg per tree to 3.5 kg on the average per tree by using the American Bark Hack method in conjunction with ______ sulfuric acid:
Options:
Answer:
It has been possible to raise the yield of resin from chir pine from the existing 1.5 kg per tree to 3.5 kg on the average per tree by using the American Bark Hack method in conjunction with 40% sulfuric acid:
