The molar conductivity of a solution of a weak acid HX (0.01 M) is 10 times smaller than the molar conductivity of a solution of a weak acid HY (0.10 M). If $$\lambda _{{x^ - }}^0 \approx \lambda _{{y^ - }}^0$$ the difference in their pK_a values, pK_a(HX) - pK_a(HY), is (consider degree of ionization of both acids to be << 1)

A closed vessel with rigid walls contains 1 mol of $${}_{92}^{238}U$$ and 1 mol of air at 298 K. Considering complete decay of $${}_{92}^{238}U$$ to $${}_{82}^{206}Pb$$, the ratio of the final pressure to the initial pressure of the system at 298 K is

In dilute aqueous H₂SO₄, the complex diaquodioxalatoferrate(II) is oxidized by $$MnO_4^-$$. For this reaction, the ratio of the rate of change of [H⁺] to the rate of change of $$[MnO_4^-]$$ is

The number of hydroxyl group(s) in Q is ___________.