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 ___________.

Among the following the number of reactions that produces benzaldehyde is _________.