Helium is an unreactive gas and neon is a gas of extremely low reactivity. What,if anything,do their atoms have in common?

Which of the given elements $A, B, C, D$ and $E$ with atomic numbers $2, 3, 7, 10$ and $30$ respectively belong to the same period?

What is the position of metalloids in the periodic table?

State whether the following statements are true or false: In the Modern Periodic Table,a zig-zag line separates metals from non-metals. The borderline elements—boron,silicon,germanium,arsenic,antimony,tellurium,and polonium—are intermediate in properties and are called metalloids or semimetals.

Which of the following statement$(s)$ about the Modern Periodic Table are incorrect?
$(i)$ The elements in the Modern Periodic Table are arranged on the basis of their decreasing atomic number.
$(ii)$ The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic masses.
$(iii)$ Isotopes are placed in adjoining group$(s)$ in the Periodic Table.
$(iv)$ The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic number.

$Lithium$,$sodium$,and $potassium$ are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?