Fuel cell, using hydrogen and oxygen as fuels, A. has been used in spaceship B. has as efficiency of 40% to produce electricity C. uses aluminium as catalysts D. is eco-friendly E. is actually a type of Galvanic cell only

To determine the correct combination of statements, let us analyze each of the given statements regarding fuel cells using hydrogen and oxygen as fuels:

Statement A: "has been used in spaceship"
This statement is correct. Hydrogen-oxygen fuel cells were famously used in the Apollo space program to provide electricity as well as clean drinking water for the astronauts.

Statement B: "has as efficiency of 40% to produce electricity"
This statement is incorrect. Fuel cells are highly efficient compared to conventional thermal power plants. The efficiency of a hydrogen-oxygen fuel cell in producing electricity is typically around 60% to 70%, rather than just 40%.

Statement C: "uses aluminium as catalysts"
This statement is incorrect. The catalysts typically used in hydrogen-oxygen fuel cells are finely divided platinum, palladium, or other noble metals, which facilitate the electrode reactions. Aluminium is not used as a catalyst in these cells.

Statement D: "is eco-friendly"
This statement is correct. The primary byproduct of a hydrogen-oxygen fuel cell is water, which makes it an extremely clean and eco-friendly source of energy with zero harmful emissions.

Statement E: "is actually a type of Galvanic cell only"
This statement is correct. A fuel cell is a galvanic (voltaic) cell that converts the chemical energy of a fuel (like hydrogen) and an oxidant (like oxygen) directly into electrical energy.

Therefore, statements A, D, and E are correct, which corresponds to the option "A,D,E only".