A cylinder containing an ideal gas (0.1 mol of 1.0 dm³) is in thermal equilibrium with a large volume of 0.5 molal aqueous solution of ethylene glycol at its freezing point. If the stoppers S₁ and S₂ (as shown in the figure) are suddenly withdrawn, the volume of the gas in litres after equilibrium is achieved will be____.

(Given, K_f (water) = 2.0 K kg mol^–1,
R = 0.08 dm³ atm K^–1 mol^–1)

How much amount of NaCl should be added to 600 g of water ($$\rho $$ = 1.00 g/mL) to decrease the freezing point of water to – 0.2 °C ? ______.
(The freezing point depression constant for water = 2K kg mol^–1)