A chemical reaction occurs between manganese (III) pyrophosphate and calcium metal. How many molecules of calcium metal are needed in this reaction?

Which statement best explains the relationship between an area is geography and the temperature of its surface water

As changes in energy levels of electrons increase, the frequencies of atomic line spectra they emit

Oil rich countries in the middle east cover about 4% of earths total land area but prossess about 48% of the worlds known oil reserves what is the main reason for high concentration of reserves in this part of the world