The displacement method for measuring volume:

is not always accurate
can be used to measure the volume of solids
may yield incorrect results if the matter is soluble in liquid
all of the above

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

they are all solids.