Consider the group 1a elements sodium (period 3), potassium (period 4), and rubidium (period 5). what would you predict about the ionization energies of these elements? na < k < rb na > k > rb c. rb < na < k d. na = k = rb

The correct answer is Na > K > Rb.  

The order predicted would be ionization energy of sodium is greater than the ionization energy of potassium, which is greater than the ionization energy of rubidium.  

The ionization energy refers to energy, which has to be supplemented to a gaseous atom in order to withdraw an electron and produce a positive ion. The ionization energy decreases in going down a group. The cause of the decline of the ionization energy down a group is that as one moves down a group, the size of the atom increases that signifies that the valence electrons get further away from the nucleus, and thus, less energy is required to withdraw the electrons.  

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.