Q3

A) Equilibrium shifts to right to maintain K value so as N2 increases it will try to decrease it by shifting  to right.(Le Chatelier's principle)
B) At equilibrium rate is spontaneous equally in both directions and hence   Detla G = 0
detla G = G(products) - G ( reactants )= 0
      2G(NH3) -[G(N2) +3G(H2))= 0 if you rearrange it you will get option B
C) Addition of catalysts changes only activation energy and nothing else.
D)Catalyst definitely increases the rate of reaction however equally in both direction.