Which of the following is not a proper iupac name?
a. 3-pentanone
b. 1-cyclopentanone
c. 2-pentanone
d. 1-pentanone

The IUPAC of 1-pentanone is not correct.

Explanation:

The structures of each of the given compounds with correct IUPAC names are shown in the figure.

In case of ketones there must be two alkyl groups attached to the carbonyl carbon. In case of aldehydes there must be atleast one hydrogen attached to carbonyl carbon.

Now if we are saying that 1-pentanone, it means we are actually naming the compound with wrong functional group. This is infact an aldehyde with the correct name as "pentanal".

Rest of the given IUPAC names are correct.

"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."

let that person have a turn to speak : )