1. Consider the following statements about hydrogen fuel cells.
The use of porous electrodes reduces cell efficiency.
II As the ratio of the amount of hydrogen supplied to the amount of electricity produced increases, the efficiency increases.
Which of the statements about hydrogen fuel cells is/are correct?
A. I only
B. II only
C. both I and II
D. neither I nor 11.

Solution

2. The overall reaction in an alkaline-ethanol fuel cell is shown below.

What amount of hydroxide ions, OH-, reacts with 1 mol of ethanol, C₂H₅0H, at the negative electrode of
the fuel cell?
A. 4mol
B. 6mol
C. 8mol
D. 12 mol

Solution

3. Consider the following statements regarding fuels.
I. Bioethanol fuel is sustainable because it results in no net release of carbon dioxide into the atmosphere.
II. Hydrogen peroxide, H₂0₂ , can be used as an oxidising agent in fuel cells.
Which of the statements regarding fuels is/are correct?
A. l only
B. II only
C. both I and II
D. neither I nor II

Solution