The mass number is
a. use the atomic number
b. mass number - atomic number
c. number of protons and neutrons in an atom

Consider the elements bromine and chlorine; which elements has a larger ionic radius ?

What material does not melt at any temperature

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