Black coffee since it is a darker colour and has a heavier taste
The spectator ions would be the ions that <em>don't </em>comprise the precipitate in this reaction. You have four ionic species here: Pb²⁺, NO₃⁻, H⁺, and SO₄²⁻. Since Pb²⁺ and SO₄²⁻ combine, as you are told, to form the precipitate, that leaves H⁺ and NO₃⁻ (or, in normal text, H+ and NO3-) to be the spectator ions.
Edit: NO3- might be interpreted ambiguously since it's not immediately clear that the NO3 is a polyatomic ion with a -1 charge and not an NO compound with a 3- charge, so it should be written as [NO3]- or (NO3)-.
The net ionic reaction shows the reaction without the spectator ions. In this case, that would be: Pb²⁺(aq) + SO₄²⁻(aq) → PbSO₄(s).
8.40 ml. I think that is right.
A. The hydrogen molecule has a structural formal that looks like this: H—H. The oxygen molecule has a structural formula that looks like this: O=O (except you should make the lines longer). When you combine the molecules, it has a structural formula that looks like this:
O
/ \
H H
b. O=C=O (again, make the lines a little longer)
c. space-filling model of hydrogen looks like this oo (circles should be touching) and the space-filling model of carbon dioxide should look like this OoO (circles should be touching)