You add 5.7 g of iron to 25.20ml of water and observe that the volume of the iron and water together is 25.92ml calculate thw density of the iron

7.92gml-1

Explanation:

water=25.20ml

water+iron=25.92ml

iron=5.7g

P=mass/volume (formula of density)

mass=5.7g

volume=25.92-25.20

=0.72ml

p=5.7/0.72

=7.92gml-1

water is used to store them because it would keep the radiation from getting out in the open and causing harm to the workers

"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."