Water is a compound. A compound is made up of two or more elements. In the case of water, or H2O, there are 2 hydrogen atoms present and 1 oxygen atom. I hope this helps you on your assignment. Good luck!
The answer is (4). You may recall hearing about the "sea of electrons" model of metals. Metals represent the ultimate case of delocalized (shared) valence electrons, and these delocalized valence electrons are what freely move around, conducting current through the body of the metal.
Electron affinity is the change in energy of an atom with a neutral charge when an electron is added to form an anion. A more negative electron affinity corresponds to a greater attraction for an electron. Electron affinity become less negative down a group and from left to right in the periodic table.
I believe the answer is diamond. Hope this helps!