2 mole of an ideal gas at \( 27^{\circ} \mathrm{C} \) temperature is expanded reversibly from 2 lit to 20 lit. Find the entropy change. \( (R=2 \mathrm{cal} / \mathrm{mol} \mathrm{K}) \) \( \begin{array}{llll}\text { (a) } 92.1 & \text { (b) } 0 & \text { (c) } 4 & \text { (d) }-9.2\end{array} \)

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

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.

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 ]

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

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