Mars has a mass of 642,000,000,000,000,000,000,000 kg. How would scientists express this number in scientific notation?

This graph gives information on changes in sea ice extent in the arctic ocean over a 30-year span. the overall trend shows in the ice extent. to address the trend, scientists need to ask themselves, one direct consequence of the trend is that

Which element would mostly likely have an electron affinity measuring closest to zero

Draw the structure for 5-isopropyl-2-methyl-3-nonene