Each of four groups of students determined and recorded the melting point of a solid compound. if the actual melting point is 113°c, which group had the best precision?

Group 4

Explanation:

Precision means the closeness of repeated measurement.

Accuracy means the closeness of measurement to its true value.

Measurement can be precise but not accurate.

Group 4 measurement has the lowest range which is 110 - 111, hence, they are the most precise in their measurement.

(See the attached image)

"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."

the answer is option a.