With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements: 1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products. 2. Fuel cells can be used for powering buildings and not for small devices like laptop computers. 3. Fuel cells produce electricity in the form of Alternating Current (AC). Which of the statements given above is/are correct?

1. Statement 1 is correct. Fuel cells combine a hydrogen-rich fuel (like pure hydrogen) and an oxidant (oxygen, usually from the air) electrochemically to generate electricity. When pure hydrogen is used, the chemical reaction is essentially 2H₂ + O₂ → 2H₂O. The only by-products are water (H₂O) and heat, making it a very clean energy conversion process. 2. Statement 2 is incorrect. While fuel cells can be used for stationary power generation (powering buildings) and transportation, they are also being developed and used for portable applications, including small devices like laptop computers, mobile phones, and other electronics, often as battery chargers or replacements. Fuel cells come in various sizes and power outputs. 3. Statement 3 is incorrect. Fuel cells, like batteries, generate electricity through an electrochemical process, which inherently produces Direct Current (DC). If Alternating Current (AC) is required, an inverter must be used to convert the DC output. 4. Therefore, only statement 1 is correct.