At 4.00 L, an expandable vessel contains 0.864 mol of oxygen gas. How many liters of oxygen gas must be added at constant temperature and pressure if you need a total of 1.96 mol of oxygen gas in the vessel?

5.07L

Explanation:

The equation to use is Avogadro's Law or  

So when you substitute your values in you end up with V2= 9.074L

To find the change you would subtract 4 to see how much you need to add which is going to be 5.07L

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )