An observation is defined as a statement or conclusion you made after observing or measuring a phenomenon, this includes statements based on precise instruments. For example, if you conclude a plant grows 2 inches every month by measuring the plant during this time, this is classified as an observation. The conclusion of the student is also an observation because he concludes this after analyzing the volume of the water in the cylinder through the lines in the graduated cylinder, considering the water is just in the middle of 100 mL and 200 mL which indicates there are 150 mL of water.
Given the illustration, such statements is considered as an observation, since it came up from something the student realized with his/her own eyes, as in the volumetric cylinder the level of the liquid reached 150 mL of water. Predictions are not observed but assumed, theories are stated when experimentation is already deeply studied and hypothesis are assumptions before experimenting.
You're going to use the PV= nRT formula. You'll add 273 to 25 to get the temperature in K and you'll plug in everything you know Into the formula. You also must change Liters into milliliters, so it will be 1200 ml. After putting everything into the formula you can solve it algebraically. The moles of gas would be about 540.19
