200mL of 12.0M HNO3 is prepared from stock solution of 16.0M HNO3. A, What volume of stock solution of NH3 is used? And b, What volume of water should be added to the stock

a. 150mL of the stock solution was added

b. 50mL of water was added

Explanation:

The solution was diluted from 16.0M to 12.0M, that is:

16.0M / 12.0M = 1.333 times was diluted.

As the volume of the diluted solution is 200mL, the amount of the 16.0M stock solution is:

200mL / 1.333 =

As the volume of the solution is 200mL and 150mL were added of the stock solution, the volume of water is:

200mL - 150mL =

"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."