In following pairs, the one in which both transition metal ions are colourless is :

In neutral or faintly alkaline medium, $$\mathrm{KMnO}_{4}$$ being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be :

Which among the following pairs has only herbicides?

Which among the following is the strongest Bronsted base?