Chemistry Question?

[David D]

1.Which one of the following is a diprotic acid?
chloric acid, sulfuric acid, phosphoric acid, nitric acid or hydrofluroric acid

2.A sulfur oxide is 50.0% by mass sulfur. This molecular formula could be what?
a. S2O4
b. SO
c. S2O
d. SO2
e. either SO2 or S2O4

3.Automotive air bags inflate when sodium azide decomposes explosively to its constituent elements:

2NaN3 (s) -> 2Na (s) + 3N2 (g)
How many grams of sodium azide are required to produce 18.0 g of nitrogen?

4.Which hydroxides are weak bases?
1) Sr(OH)2
2) KOH
3) NaOH
4) Ba(OH)2

5.With which of the following will ammonium ion form an insoluble salt?
a. sulfate
b. sulfate and carbonate
c. carbonate
d. chloride
e. none of the above
Need answer thanks!