What is 2.1 x 10^6 + 6.2 x 10^7 in scientific notation

How many moles are equivalent to 55.5g of nano3

Which statement is a reason to support population regulation? a) it is unethical for us to control birth control rates b) humans have the freedom to produce as many children as desired c) the gap between the rich and poor has been narrowing since 1960 d) billions more people on the earth will intensify many environmental and social problems

What are scientists who study fossils called? ( a ) astronomers. ( b ) biologists. ( c ) geologists. ( d ) paleontologists.