Which pair of solutes could be used to prepare an aqueous buffer solution with a ph < 7?

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

How does concentration affect reaction rate

Use the measurements in the table to determine which unidentified metal has the highest density. metal volume mass a 10.5 cm3 122 g b 14.2 cm3 132 g c 16.1 cm3 115 g d 12.7 cm3 126 g