1. The "Pop" Test:

* Procedure: Bring a lit match or a burning splint (a small stick) near the suspected hydrogen gas.

* Observation: If hydrogen is present, it will react with the flame, producing a high-pitched "pop" sound. This is due to the rapid combustion of hydrogen, forming water vapor.

2. Reduction of Metal Oxides:

* Procedure: Pass the suspected hydrogen gas over heated copper oxide (CuO) or iron oxide (FeO).

* Observation: If hydrogen is present, it will reduce the metal oxides to their elemental forms, forming water vapor. You'll observe a change in color, e.g., black CuO turning reddish-brown as copper metal is formed.

3. Flame Test:

* Procedure: Pass the suspected hydrogen gas through a flame.

* Observation: If hydrogen is present, the flame will turn pale blue.

4. Chemical Analysis:

* Procedure: Use analytical techniques like gas chromatography or mass spectrometry.

* Observation: These methods can identify the presence of hydrogen gas by detecting its specific molecular weight and chemical signature.

Important Note: Always exercise caution when dealing with flammable gases like hydrogen. Ensure proper ventilation and take necessary safety precautions.