Histidine has ionizable groups with pKa values of 1.8, 6.0 and 9.2. (These correspond to the COOH, imidazole, and –NH3 groups respectively). You have 100 mL of a 0.1 M solution of histidine at pH 5.40. You then add 40 mL of 0.1 N HCl. What is the resulting pH of the solution?

can you attach a picture of the lettuce? : )

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.