Read the following passage given below and answer the question.
Production of electricity by thermal plants is not very efficient method. It is now possible to make cells in which reactants are fed continuously to the electrodes and products are also removed continuously. One of the most successful fuel cells is hydrogen fuel cell.
Which is not true for fuel cell?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Not cost effective
The passage presents the fuel cell as a better way of producing electricity than a thermal plant. Its features are: it is efficient (about 70%), it is pollution free, and the \( \ce{H2-O2} \) cell supplied power in the Apollo space programme, its water being used by the astronauts.
Option (1) Efficient — A feature of the fuel cell. It converts chemical energy directly into electricity with about 70% efficiency.
Option (2) Not cost effective — Not a feature given for the fuel cell. The features listed for the fuel cell are its high efficiency, freedom from pollution and its use in space; being “not cost effective” is not one of them.
Option (3) Pollution free — A feature of the fuel cell. The only product of the \( \ce{H2-O2} \) cell is water.
Option (4) Can be used by astronauts — A feature of the fuel cell. The cell powered the Apollo missions, and its water was added to the astronauts’ drinking supply.
NCERT (2026-27 edition):
Fuel Cells – “… One of the most successful fuel cells uses the reaction of hydrogen with oxygen to form water (Fig. 2.12). The cell was used for providing electrical power in the Apollo space programme. The water vapours produced during the reaction were condensed and added to the drinking water supply for the astronauts.”
Fuel Cells – “… The cell runs continuously as long as the reactants are supplied. Fuel cells produce electricity with an efficiency of about 70 % compared to thermal plants whose efficiency is about 40%. There has been tremendous progress in the development of new electrode materials, better catalysts and electrolytes for increasing the efficiency of fuel cells. These have been used in automobiles on an experimental basis. Fuel cells are pollution free and in view of their future importance, a variety of fuel cells have been fabricated and tried.”