The species in which the central atom uses sp² hybrid orbitals in its bonding is

Arrange the following :

N₂, O₂, F₂, Cl₂ in increasing order of bond dissociation energy

Write down the balanced equation for the reaction when:
Carbon dioxide is passed through a concentrated aqueous solution of sodium chloride saturated with ammonia.

Urn $$A$$ contains $$6$$ red and $$4$$ black balls and urn $$B$$ contains $$4$$ red and $$6$$ black balls. One ball is drawn at random from urn $$A$$ and placed in urn $$B$$. The one ball is drawn at random from urn $$B$$ and placed in urn $$A$$. If one ball is now drawn at random from urn $$A$$, the probability that it is found to be red is ................