One million atoms of a particular element have a mass of 1.99 ×10^-17 grams. how many moles of this element are there?

Can you guys me with question no. 5!

Which element would mostly likely have an electron affinity measuring closest to zero

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?