Which property of substance is not altered by a physical change?

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

Which other elements contain the same number of outer electrons as sodium

According to the valence shell electron pair repulsion (vsepr) theory, a molecule that has four electron groups around the central atom will exhibit what electron geometry? view available hint(s) according to the valence shell electron pair repulsion (vsepr) theory, a molecule that has four electron groups around the central atom will exhibit what electron geometry? trigonal bipyramidal tetrahedral square planar determination of electron geometry requires information on whether the electron groups are lone pairs or bonding groups.