Jerome had read about plate tectonics and the mid-Atlantic ridge. He investigated by reading further, learning that evidence existed to show volcanic activity was happening along the mid-Atlantic ridge. How do the pillow-shaped rocks found there provide evidence that volcanic activity is taking place? A. They form only when molten material cools slowly in warm water. B. They form only along subduction zones in the trenches of the Atlantic. C. They form only when lava erupts above the water when the air is cool. D. They form only when molten material hardens quickly in cold water.

The atomic radius of sodium is 186 pm and of chlorine is 100 pm. the ionic radius for na+ is 102 pm and for cl– is 181 pm. in going from na to cl in period 3, why does the atomic radius decrease while the ionic radius increases? a. the inner electrons in the sodium cation shield its valence electrons more effectively than the inner electrons in the chloride anion do. b. the inner electrons shield the valence electrons more effectively in the chlorine atom than in the chloride anion. c. the outermost electrons in chloride experience a smaller effective nuclear charge than those in the sodium cation do. d. the outermost electrons in chloride experience a larger effective nuclear charge than those in the sodium cation do. e. monatomic ions are bigger than the atoms from which they are formed.