In the flame test of a mixture of salts, a green flame with blue centre was observed. Which one of the following cations may be present?

A company dissolves 'x' amount of CO₂ at 298 K in 1 litre of water to prepare soda water. X = __________ $$\times$$ 10^$$-$$3 g. (nearest integer)

(Given : partial pressure of CO₂ at 298 K = 0.835 bar.

Henry's law constant for CO₂ at 298 K = 1.67 kbar.

Atomic mass of H, C and O is 1, 12, and 6 g mol^$$-$$1, respectively)

PCl₅ dissociates as

PCl₅(g) $$\rightleftharpoons$$ PCl₃(g) + Cl₂(g)

5 moles of PCl₅ are placed in a 200 litre vessel which contains 2 moles of N₂ and is maintained at 600 K. The equilibrium pressure is 2.46 atm. The equilibrium constant K_p for the dissociation of PCl₅ is __________ $$\times$$ 10^$$-$$3. (nearest integer)

(Given : R = 0.082 L atm K^$$-$$1 mol^$$-$$1; Assume ideal gas behaviour)

The resistance of a conductivity cell containing 0.01 M KCl solution at 298 K is 1750 $$\Omega$$. If the conductivity of 0.01 M KCl solution at 298 K is 0.152 $$\times$$ 10^$$-$$3 S cm^$$-$$1, then the cell constant of the conductivity cell is ____________ $$\times$$ 10^$$-$$3 cm^$$-$$1.