carbon dioxide...
None, no gas is given off.
Ammonia gas (NH3) is given off when ammonia solution is heated.
Reticulated (tap) water is usually chlorinated with either chlorine (gas) or chloramine (liquid). Given time, the gas (chlorine) will evaporate off leaving the water uncontaminated and suitable for fish to live in. The chloramine though needs to be neutralised by the addition of a chemical that can be purchased at pet shops.
hydrogen eg:Na+HCl------>NaCl+H2
Hydrogen gas is given off when magnesium reacts with sulfuric acid.
Carbon Dioxide is given off. (CO2)
Hydrogen gas.
Oxygen gas
Hydrogen gas is always given off when an acid solution is electrolyzed.
When you place a lighted splint into, say, a test tube, where you suspect hydrogen gas is being given off, a 'pop' sound indicates the presence of the gas.
Oxygen is given of
Oxygen