10. Cuando se intenta nombrar un compuesto se debe tener en cuenta los estados de oxidación de los elementos y que estos por regla al sumarlos deben dar cero. Con base en esto, el estado de oxidación del Cr en el compuesto \( \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \) es: \( \begin{array}{ll}\text { A. }+1 & \text { C. }+7 \\ \text { B. }-6 & \text { D. }+6\end{array} \)

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

Which of the following represent a buffer system? Check all that apply. \( \square \mathrm{NaOH} \) and NaCl \( \square \mathrm{H}_{2} \mathrm{CO}_{3} \) and \( \mathrm{NaHCO}_{3} \) HF and KF KCl and NaCl

Please select the molecule(s) with resonance structures from the following. CCl 4 CHCl 3 SO 3 H 2 O None

If an endothermic reaction is at equilibrium, how will the equilibrium shift when heat is added to the reaction? View Available Hint(s) The reaction will shift toward the reactants. The reaction will shift toward the products. The reaction will not shift toward products or reactants. The reaction will shift toward both reactants and products.

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. \( \left[\mathrm{H}^{*}\right]=\square \)