What is 823,549 rounded to three significant figures?

Which uses electromagnetic radiation to discover the properties and composition of bodies in space? space probe space station space shuttle space observatory

What are the first three quantum numbers for the electrons located in subshell 2s?

Which ocean zone has the most abundant primary producer and why a) the abyssopelagic zone ,du to the absence of light and cold water temperatureb) the bathypelagic zone, due to the absence of light and cold water temperaturec) the mesopelagic zone ,due to uts high light availability and warm water temperature d) the epipelagic zone, due to its high light availability and warm water temperature