The OH^$$-$$ concentration in a mixture of 5.0 mL of 0.0504 M NH₄Cl and 2 mL of 0.0210 M NH₃ solution is x $$\times$$ 10^$$-$$6 M. The value of x is ___________. (Nearest integer)

[Given K_w = 1 $$\times$$ 10^$$-$$14 and K_b = 1.8 $$\times$$ 10^$$-$$5]

The number of 4f electrons in the ground statement electronic configuration of Gd²⁺ is ___________. [Atomic number of Gd = 64]

The ratio of number of water molecules in Mohr's salt and potash alum is ____________ $$\times$$ 10^$$-$$1. (Integer answer)

The following data was obtained for chemical reaction given below at 975 K.

2NO_(g) + 2H_2(g) $$\to$$ N_2(g) + 2H₂O_(g)



The order of the reaction with respect to NO is ___________. [Integer answer]