Gas X is a waste gas from digestion in animals. Gas Y is formed when gas X is burnt with a small amount of oxygen. Gas Z is formed when gas X is burnt with an excess of oxygen. <br/>What are X, Y and Z?

• AX: Carbon dioxide, Y: Methane, Z: Carbon monoxide
• BX: Carbon monoxide, Y: Methane, Z: Carbon dioxide
• CX: Methane, Y: Carbon dioxide, Z: Carbon monoxide
• DX: Methane, Y: Carbon monoxide, Z: Carbon dioxide

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