Which of the following is the wrong statement?

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

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

For gaseous state, if most probable speed is denoted by C*, average speed by $$\mathop C\limits^{\_\_} $$ and mean square speed by C, then for a large number of molecules the ratios of these speeds are: