What three things must happen in order for a theory to be formed? someone can give a resume?​

Consider the two electron arrangements for neutral atoms a and b. are atoms a and b the same element? a - 1s2, 2s2, 2p6, 3s1 b - 1s2, 2s2, 2p6, 5s1

If a plot weight (in g) vs. volume (in ml) for a metal gave the equation y= 13.41x and r^2=0.9981 what is the density of the metal?

Consider the nuclear equation below. 239/94 pu—-> x+ 4/2 he. what is x?