Element A has a molar mass of 1.41 g , element D has a molar mass of 66.58 g , and element E has a molar mass of 2.09 g . What is the molar mass of the compound \( \mathrm{A}_{3} \mathrm{D}_{4} \mathrm{E}_{2} \) ? Give your answer to the hundredths place in \( \mathrm{g} / \mathrm{mol} \). Do not put units in the answer space.

Which of the following molecule(s) have lone pair electrons and/or non-identical central bonds? NH3 BF3 PF5 PF3

Based on your worksheet results, please match the following: [he molecular shape of NH 3 is [Choose ] [Choose ] [Choose ] [Che molecular shape of BF3 is [Choose] The molecular shape of PF3 is

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 ]

Please select the molecule(s) with double bond(s) from the following. \( \mathrm{CCl}^{2} \) CHCl 3 CO 3 H 2 O None

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.