What volume (ml) of concentrated HNO3 (15.8 M) should be used to prepare 250.0 ml of a 0.400 M solution?

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Type the letter that represents the correct location for each particle type below.

The table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 9 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of tthe table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 9 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.