The pair of compounds having metals in their highest oxidation state is

According to molecular orbital theory which of the following statement about the magnetic character and bond order is correct regarding $$O_2^+$$

A sodium salt on treatment with MgCl₃ gives white precipitate only on heating. The anion of the sodium salt is

The value of the integral $$\int\limits_0^1 {\sqrt {{{1 - x} \over {1 + x}}} dx} $$ is