The pH scale for acidity is defined by \[ \mathrm{pH}=-\log \left[\mathrm{H}^{+}\right] \] where \( \left[\mathrm{H}^{+}\right] \)is the concentration of hydrogen ions measured in moles per liter (M). a) A sample of rhubarb is found to have a hydrogen concentration of 0.000501 M . What is the pH? Round your answer to 2 decimal places. \( \mathrm{pH}=\square \) b) The pH of a sample of red onion is 5.40 . What is the hydrogen concentration? Keep at leost 2 non-zero decimal ploces. \( \left[\mathrm{H}^{*}\right]=\square \)

Based on your worksheet results, please match the following: The electron group geometry of NH 3 is The electron group geometry of BF 3 is [Choose ] The electron group geometry of \( \mathrm{PF5} \) is [Choose ] [Choose ] electron group geometry of SF4 is geometry of PF 3 is [Choose ]

L'uraninite, ou pechblende, est un minéral de formule chimique \( \mathrm{UO}_{2} \). Les gisements d'uraninite sont datés uniquement entre 3,5 et 2,2 milliards d'années. Its sont utilisés notamment pour extraire l'uranium uti- lisé dans l'industrie nucléaire civile et militaire. Ces gisements se forment dans des milieux réducteurs, c'est-à-dire en absence de dioxygène. Question Expliquer en quoi l'uraninite est un indice de l'évolution de la teneur en dioxygène terrestre.

Please select polar molecule(s) from the following. \( \square \mathrm{CCl} 4 \) \( \square \mathrm{CHCl} 3 \) \( \square \mathrm{CO} 3 \) CO 2

Please select the molecule(s) that 1) its molecular shape is different from its electron group shape, and/or 2) the central bonds are not identical. NH3 BF3 PFF PF3

Please select polar molecule(s) from the following. NH3 BF3 PF5 PF3