Nitrogen when combined with oxygen can form various oxides. 3.5g of nitrogen gas is burned in oxygen to form 11.5 g of an oxide of nitrogen. a) Determine the mass of oxygen burned. (HINT: the oxide contains only nitrogen and oxygen) b) Using data from the experiment find the percent of nitrogen by mass in the oxide. I'm stuck on b)! Help! :(

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e