7. Which of the following changes could be associated with either a chemical change OR a physical change?
a. The change cannot be reversed
b. Bending of metal
c. New substances formed
d. Change in color

a: chemical change because the change cannot be reversed.

b: physical change because the action can be reversed.

c: chemical change.

d:chemical change.

any change that cannot be reversed is a chemical change and any change that can be reversed is a physical change.

"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."

it would be a gas formation