2. Which of the following are flammable gases?
   a) Hydrogen
   b) Oxygen
   c) Methane
   d) Both A & C

Hydrogen and methane are both highly flammable gases that can easily ignite in the presence of an open flame or spark. Hydrogen is known for its explosive potential when mixed with air, while methane, commonly found in natural gas, is frequently used as a fuel source due to its combustibility. Always handle these gases with care!

In real-world applications, flammable gases are utilized in various industries, particularly in energy and manufacturing. For example, methane powers residential heating and cooking devices, while hydrogen is increasingly being explored as a clean energy source for fuel cells in vehicles. Safety measures like proper ventilation and leak detection systems are crucial when working with these gases to prevent accidents.