The number of N atoms in 681 g of C₇H₅N₃O₆ is x $$\times$$ 10²¹. The value of x is (N_A = 6.02 $$\times$$ 10²³ mol^$$-$$1) (Nearest Integer)

The distance between Na⁺ and Cl^$$-$$ ions in solid NaCl of density 43.1 g cm^$$-$$3 is _______________ $$\times$$ 10^$$-$$10 m. (Nearest Integer)

(Given : N_A = 6.02 $$\times$$ 10²³ mol^$$-$$1)

The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x $$\times$$ 10^$$-$$8 m. The value of x is ___________. (Nearest Integer).

(Given : Energy of the electron in the first shell of the hydrogen atom is $$-$$2.2 $$\times$$ 10^$$-$$18 J ; h = 6.63 $$\times$$ 10^$$-$$34 Js and c = 3 $$\times$$ 10⁸ ms^$$-$$1)

The standard entropy change for the reaction

4Fe(s) + 3O₂(g) $$\to$$ 2Fe₂O₃(s) is $$-$$550 J K^$$-$$1 at 298 K.

[Given : The standard enthalpy change for the reaction is $$-$$165 kJ mol^$$-$$1]. The temperature in K at which the reaction attains equilibrium is _____________. (Nearest Integer)