When you need heat to make reaction happen it is endothermic.
If heat was on the right side then type of reaction would be exothermic.
The noble gases are helium, neon, argon, krypton, xenon, radon, and ununoctium. The noble gases are relatively nonreactive. This is because they have a completevalence shell<span>. They have little tendency to </span>gain<span> or lose </span>electrons. <span>These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical </span>reactivity<span>. The six noble gases that occur naturally are helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).</span>
Mass per unit volume is nothing but density of an body density = Mass/Volume. hope this helps. :)
It's hard to relate a mole to carbon or sulfur. Imagine if I walked up to you and said, "What's the relation between a dozen and donuts?"
A mole is a form of measurement for atoms, more specifically, 6.02 * 10^23 atoms. I suppose you could relate it to Carbon or Sulfur, since the number of atoms of each are usually measured in moles.
Carbon and Sulfur don't have a set number of moles (Just like donuts don't have to be a dozen), so it's hard to answer your second question.
In the atomic table, the number you see under the element is the molar mass, which is the weight of an a mole of the element. In this way, I guess there's a mole of Carbon and Sulfur present, if we're looking at the periodic table.
-T.B.