I need help please with questions 35+38

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

How many liters of water can be produced from 5.0liters of butane gas at stp, assuming excess oxygen? c4h10(g) + 02(g) → co2 (e) + h2o (g)

When hydrogen peroxide (h2o2) is added to potassium iodide (ki) solution, the hydrogen peroxide decomposes into water (h2o) and oxygen (o2). the chemical equation for the decomposition reaction is: 2h2o2—> 2h2o + o2. what is the role of the potassium iodide in this reaction? a. reactant. b. product. c. precipitate. d. catalyst.