10.30 mg of O₂ is dissolved into a liter of sea water of density 1.03 g/mL. The concentration of O₂ in ppm is__________.

The sum of the total number of bonds between chromium and oxygen atoms in chromate and dichromate ions is ____________.

A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The activa tion energy (in kJ/ mol) for this process is closest to__________.

(Given, R = 8.3 J mol^–1 K^–1, $$\ln \left( {{3 \over 2}} \right) = 0.4$$, e^–3 = 4.0)

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 If the stoppers S₁ and S₂ (as shown in the figure) are suddenly withdrawn, the volume of the gas in litres after equilibrium is achieved will be____.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)