The microsphere nanoscope is a powerful tool that allows humans to see structures 9 × 10–9 meter in diameter. How is this number expressed in standard form?

Several paint mixtures are made by mixing blue paint and white paint. paint colors blue paint white paint mixture a 5 cups 12 cups mixture b 6 cups 6 cups mixture c 4 cups 12 cups mixture d 5 cups 6 cups which mixture has the highest ratio of blue paint to white paint