(a) \( \mathrm{SiBr}_{4} \) tristorted tetrahedron (b) \( \mathrm{CS}_{2} \) trigonal pyramidal trigonal planar trigonal pyramidal (c) \( \mathrm{NO}_{3}^{-} \) trigonal planar bent trigonal pyramidal tetrahedral to

Question B 2 The following redox reaction is used in acidic solution in the Breathalyzer test to determine the level of alcohol in th blood of drunk drivers: \[ \mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{5} \rightarrow \mathrm{Cr}^{3+}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O} \] a) Identify the elements undergoing changes in oxidation state and indicate the initial and final oxidation numbers for theseelements.

Un laboratorio requiere de \( 2000 \mathrm{~cm}^{3} \) de una solución anticongelante que consiste en \( 30 \% \) mol de metanol en agua ¿Qué volúmenes de metanol puro y de agua pura a \( 25^{\circ} \mathrm{C} \) se deben mezclar para formar los \( 2000 \mathrm{~cm}^{3} \) de anticongelante tambièn a \( 25^{\circ} \mathrm{C} \) ? Asuma qué es una solución ideal. Los volúmenes molares parciales para el metanol y el agua en una solución de \( 30 \% \) mol de metanol y sus volumenes molares de especie pura ambos a \( 25^{\circ} \mathrm{C} \) son los siguientes: Metanol (1) \( \quad \overline{V_{1}}=38.632 \mathrm{~cm}^{3} / \mathrm{mol} \quad V_{1}=40.727 \mathrm{~cm}^{3} / \mathrm{mol} \) Calcule además el error que se produce al asumir que la solucion es ideal.

Question B2 The following redox reaction is used in acidic solution in the Breathalyzer test to determine the level of alcohol in tl] blood of drunk drivers: \[ \mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{5} \rightarrow \mathrm{Cr}^{3+}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O} \] a) Identify the elements undergoing changes in oxidation state and indicate the initial and final oxidation numbers for these elements. [5] b) Write and balance the oxidation half-reaction.[6] c) Write and balance the reduction half reaction.[6] d) Combine the half-reactions to produce a balanced redox reaction. [3]

Select the single best answer. Which of the following describes the bonding in the hydrogen cyanide molecule, HCN? As N is \( s p \)-hybridized. C uses \( s p \) hybridized orbitals in bonding. C uses \( s p^{2} \) hybridized orbitals in bonding. C uses \( s p^{3} \) hybridized orbitals in bonding. C uses \( s p^{3} d \) hybridized orbitals in bonding.

The density of \( \mathrm{SO}_{2} \) and \( \mathrm{CO}_{2} \) are \( 2.9 \mathrm{~g} / \mathrm{dm}^{3} \) and \( 1.98 \mathrm{~g} / \mathrm{dm}^{3} \) respectively. How much faster does \( \mathrm{CO}_{2} \) diffuse through a porous pot?