A student obtained the following data during an experimental determination of the empirical formula of an oxide of tin:
- Mass of tin before heating = 1.78 g
- Mass of oxide of tin after heating to a constant mass = 2.26 g
According to these data, what is the correct formula of the oxide of tin?
a. SnO
b. SnO2
c. SnO3
d. SnO5