Chemistry Question!!!Pls help

Put separately each of the 6 solutions to a test tube. Then, heat the solutions with a Bunsen burnerto dryness.

Four of the solutions give no residue, and they are then identified.
A vinegar smell gas (ethanoic acid vapour) is given off : dilute ethanoic acid
A white mist (hydrogen chloride gas) is given off : dilute hydrochloric acid
A toilet-like pungent gas is given off : dilute ammonia solution
No other observable change : distilled water

Two of the solutions give white residues, and they have not yet beenidentified. They are dilute sodiumhydroxide and dilute sodium chloride solution.

Heat the two unidentified solutions and dilute hydrochloric acid (which has beenidentified) to make them more concentrated, and then cool to roomtemperature. Add separately thehydrochloric acid to the two unidentified solution. Then, feel the test tubes.If neutralization occurs, the test tube feels warm.
The test tube feel warm : dilute sodium hydroxide solution
The test tube does not give heat : dilute sodium chloride solution

To tsz****** :

Tasting is NOT considered as an acceptable method !

One of the first ways that scientists identified acids was to says that acids are

substance that taste sour. The sourer the substance, the more acidic it is. Now

scientist measure acidity by using the pH scale. The scale goes from 1 to 14.

Acids have a pH below 7. The lower the pH, the more acidic it is. Bases, which

are double(alkalis),have a pH greater than 7. The higher the pH, he more basic it is.
A pH of 7 is NEUTRAL that is, it is neither acidic nor basic. Water usually has a

pH of 7 ;

it tastes neither sour nor bitter.

Instruments such as pH meters and pH probes can be used to give a digital

readout of the pH of a solution. Alternatively, you can use an INDICATOR. This

is a substance that changes colour when you change the pH of the solution,

showing what change has taken place