The molarity of a solution obtained by mixing 750 mL of 0.5 (M) HCl with 250 mL of 2(M) HCl will be:

A solution of (–$$l$$) – chloro –1 – phenylethane in toluene racemises slowly in the presence of a small amount of SbCl₅, due to the formation of :

Stability of the species Li₂, $$Li_2^−$$ and $$Li_2^+$$ increases in the order of:

In which of the following pairs of molecules/ions, both the species are not likely to exist?