Question

Which of the following anions is not tested with layer test?
A. Bromide
B. Iodide
C. Chloride
D. None of the above

Answer 1

Hint: The concept of layer test used for the presence of halogens which is detected on the basis of the colour which is the colour of the layer formed is to be taken into consideration and one among these anions forms a colourless layer and this fact gives you the correct answer.

Complete answer:
We are familiar with the concept of the layer test from our lower classes of chemistry that is carried out in the laboratories.
We shall now see what does the layer test mean what reagent does it make use of and also deduce the required answer based on these facts.
- Layer test in chemistry is the test usually carried out for the detection of the halogens present. The presence of the halogens is indicated by the colour formed in the layer.
- Layer test is carried out by the addition of carbon disulphide in the presence of dilute hydrochloric acid to the given anionic solution.
Thus, on the basis of the colour formed, we can identify which halogen is present.
- In option A), bromide ion when subjected to the layer test then the colour of the layer formed is orange and therefore, the layer test is positive for this anion.
- In option B), the iodide ion when subjected to layer test, the colour of the layer formed in this case will be violet and hence layer test will be positive for this anion.
Now, in option C) the chloride ion when subjected to the layer test gives the colourless layer and thus gives a negative result for this anion.

Therefore, the correct answer for this question will be option C) Chloride.

Note:
Note that the presence of halogens is also carried out by the test called as the Lassaigne’s test which is the sodium fusion test and is used in the elemental analysis of halogens as well as nitrogen and sulphur in an organic compound.