In graph of atomic volume versus atomic weight, the elements corresponding to peaks in the curve belong to

Step-by-step solution

If we see the atomic mass versus atomic volume curve, we will notice the following features: Alkali metals such as Na,   K,   Rb which have similar properties occur as peaks of the curve. Halogen elements like F,   Cl,   Br, which have similar properties occur at the rising or the ascending part of the curve. Noble gases such as Ne,   Ar,   Kr which have similar properties occur just before the alkali elements. Hydrogen and Helium seem to be exception to the rule.