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?

Statement 1 is correct because fuel cells generate electricity through an electrochemical reaction where hydrogen and oxygen combine to produce water and heat as the only by-products. Statements 2 and 3 are incorrect because fuel cells are highly scalable—powering everything from laptops to large buildings—and they inherently produce Direct Current (DC), not Alternating Current (AC). The core concept tested is the fundamental mechanism, output characteristics, and versatile applications of hydrogen fuel cell technology.