How much Cu-64 (half-life about 12 hours) would remain from a 2 mg sample after 12 hours? Reported if not real answers, I need this to graduate

If you add 5.00 ml of 0.100 m sodium hydroxide to 50.0 ml of acetate buffer that is 0.100 m in both acetic acid and sodium acetate, what is the ph of the resulting solution? acetic acid: ka = 1.8. x 10-5

Which of these is not an example of chemical weathering? a. iron-rich mineral rusting b. feldspar turning into clay c. limestone reacting with acid d. granite breaking up into sand

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)