CGPET 2011 Solved Paper

Consider the following statements.
(1) Fuel cells are voltaic cell which convert electrical energy of fuel into chemical energy.
(2) Fuel cells are galvanic cells which convert chemical energy of fuel into electrical energy.
(3) The efficiency of H2−O2 fuel cell is approximately 25%.
(4) Fuel cells do not cause pollution problem.
Among these, the correct statements are