A simple calorimeter was set up to determine the enthalpy change occurring when one mole of ethanol is combusted. The experimental value was found to be $- 867{\text{ kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}$. The Data Booklet value is $- 1367{\text{ kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}$ (at 298 K and $1.01 \times {10^5}{\text{ Pa}}$).

During the experiment some black soot formed.

Which statements are correct?

I.     The percentage error for the experiment can be calculated as follows:

$$(1367 - 867) \times 100\%$$

II.     The difference between the two values may be due to heat loss to the surroundings.

III.     The black soot suggests that incomplete combustion occurred.

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

C