Hydrogen I. Also known as inflammable air II. Most abundant element in the earth's crust III. Stored in red cylinders

• A. I only
• B. I, II
• C. III only
• D. I, III

Answer: (D)

Hydrogen is known as inflammable air because it catches fire very easily. It is not the most abundant element in the earth’s crust—that distinction goes to oxygen. In many safety color codes, flammable gases are stored in red cylinders, so hydrogen is kept in red cylinders to warn handlers of its flammability. Therefore, statements I and III are true, while II is false. The correct conclusion is that hydrogen is inflammable and stored in red cylinders.