Astudent swings his keychain around in a circle. what is the source of the centripetal force for this action?

2positives of biotechnology: 1. plants have become more resistant to viruses and other communicable pests.2. with the of biotechnology, we have been able to produce better tasting fruits as well as vegetables.2 negatives of biotechnology: 1. biotechnology poses a number of environmental threats. genetically modifies crops often infect monarch butterflies and other insect species.2. viruses could combine with crops.

Here is the link to the all information u need i mean answer key

Use a magnet to separate iron, evaporate water, i'm not sure how to separate the other two i'm sorry but good luck